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1
Hamadto, Mohammed El Fatih Mukhtar. "Expansive soil behaviour and the development of a knowledge based system associated with foundations in expansive soils." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/526.
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Srinivasamurthy, Lakshmikanth. "Initial Swelling Mechanism of Expansive Clays: A Molecular Dynamics Study." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26647.
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Expansive soils are widely found in many parts of the world. Highly active smectite clay mineral Montmorillonite is the major constituent in these clays and can expand or contract up to 15 times of their original volume. Constrained swelling exert large amount of stress causing damage to structures, pavements etc. These clays are also used as barrier materials, Nano-materials in polymer clay Nano composites and drug delivery systems. Several factors influence the swelling potential such as water content, density, voids, electrolyte content and cation exchange capacity. However, molecular scale mechanisms that control swelling behavior in these clays need to be understood. Objectives of this research are to provide an insight into mechanisms that result in swelling of these clays. Molecular modeling is used to build and study solvation of Na-Montmorillonite system. Trajectories of water molecules are captured and the evolutions of interaction energies with swelling are calculated.
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Udukumburage, Rajitha Shehan. "Investigation of climatic-induced ground responses in expansive soils." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/198195/1/Rajitha%20Shehan_Udukumburage_Thesis.pdf.
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This thesis presents a practical approach for geotechnical practitioners to investigate the climatic-induced ground responses in expansive soils. The method is based on a novel long-term operable instrumented soil column (ISC). This research investigated the applicability of the current displacement models to the Australian context. As a result, the structural damages and maintenance costs due to cracking of light-weight structures founded on such soils can be minimised, and more importantly, the hazards to human lives can be prevented by improved decisions.
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Thomas, Pamela J. "Quantifying Properties and Variability of Expansive Soils in Selected Map Units." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30441.
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A study of 12 expansive soils in four major physiographic provinces in Virginia was initiated to examine and quantify the relationship between shrink-swell potential, shrink-swell indices, and soil properties. The mineralogy classes, soil series, and (physiographic provinces, parent materials) examined include smectitic -- Jackland and Waxpool (Triassic, diabase), Iredell (Piedmont, hornblende); vermiculitic -- Kelly (Triassic, thermal shale); kaolinitic -- Cecil (Piedmont, granite gneiss), Davidson (Triassic, diabase); and mixed -- Carbo and Frederick (Valley and Ridge, limestone), Craven and Peawick (Coastal Plain, fluvial and marine sediments), and Mayodan and Creedmoor (Triassic, sandstones). Three sites in each of the 12 map units were described and major horizons sampled for physical, chemical, and mineralogical laboratory analysis. An expansive soil rating system, termed the Expansive Soil Index (ESI), was developed using the soil properties best correlated with shrink-swell potential. The sum of swelling 2:1 minerals, swell index, liquid limit, and CEC gave expansive soil potential ratings (ESI) for each soil series. The higher the ESI, the greater the shrink-swell potential.
Smectite distributions within the soil profiles were investigated. Smectite concentration in the clay fraction increases with depth in soils formed from diabase and thermally altered shale. Smectite weathers to kaolinite and hydroxy-interlayered vermiculite with increasing proximity to the soil surface thus accounting for the observed decrease in smectite toward the soil surface. The highest amount of smectite from the granite gneiss, limestone, sandstones and shales, and Coastal Plain sediments were in the Bt2 horizon where maximum expression of the argillic horizon occurs. Smectite contents decrease away (upwards and downwards) from the maximum in the Bt2 horizon.
A satellite study focused on locating and quantifying the variability within five map units in the Culpeper (Triassic) Basin in northern Virginia. Variability of the shrink-swell indices and related properties are high in all map units. Dissimilar inclusions could adversely affect foundations if a home is sited on both moderate and high shrink-swell soils. Although there is extreme variability in the map units, the variability occurs within the delineations of each map unit. Each delineation within an individual map unit contains similar levels of variability.Ph. D.
5
Sapaz, Burak. "Lateral Versus Vertical Swell Pressures In Expansive Soils." Master's thesis, METU, 2004. http://etd.lib.metu.edu/upload/1053040/index.pdf.
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Expansive or swelling soils, exist in many part of the world, show excessive volume changes with increasing water content. As a result of this volume increase, expansive soils apply vertical and lateral pressures to the structures located or buried in these regions. Many researchs have been carried out on vertical swelling pressures helping to the engineers to design structures withstanding on these stresses. However, lateral swell behaviour of swelling soils have not been fully understood yet. Structures such asbasement walls, water tanks, canals, tunnels, underground conduits and swimming pools which will be built in expansive soils have to be designed to overcome the lateral swelling pressures as well as the other lateral pressures exerted by the soil. For this aim accurate and reliable methods are needed to predict the magnitude of lateral swelling pressures of expansive soils and to understand the lateral swelling behaviour of expansive soils. In this experimental study, the lateral swelling behaviour of an highly expansive clay is investigated using a modified thin wall oedometer which was developed in the METU Civil Engineering Department Soil Mechanics Laboratory earlier. Statically compacted samples were used in constant volume swell (CVS) tests to measure the magnitude of the lateral and vertical swelling pressures. To study the relationship between the lateral and vertical sweeling pressures, they were measured simultaneously. The samples having different initial water contents and different initial dry densities were used to study the effects of these variables on the vertical and the lateral swelling pressures. It is observed that both lateral and vertical pressures increases with increasing initial dry density and they decrease with increasing initial water content. Swell pressure ratio, the ratio of lateral swelling pressure to the vertical one, is increasing with increasing initial water content. Time needed to obtain the magnitude of maximum lateral and vertical pressures decreases with increasing initial water content and increases with increasing initial dry density.
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Baser, Onur. "Stabilization Of Expansive Soils Using Waste Marble Dust." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610339/index.pdf.
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Expansive soils occurring in arid and semi-arid climate regions of the world
cause serious problems on civil engineering structures. Such soils swell when
given an access to water and shrink when they dry out. Several attempts are being
made to control the swell-shrink behavior of these soils. Soil stabilization using
chemical admixtures is the oldest and most widespread method of ground
improvement. In this study, waste limestone dust and waste dolomitic marble
dust, by-products of marble industry, were used for stabilization of expansive
soils. The expansive soil is prepared in laboratory as a mixture of kaolinite and
bentonite. Waste limestone dust and waste dolomitic marble dust were added to
the expansive soil with predetermined percentage of stabilizer varying from 0 to 30 percent. Grain size distribution, consistency limits, chemical and
mineralogical composition, swelling percentage, and rate of swell were
determined for the samples. Swelling percentage decreased and rate of swell
increased with increasing stabilizer percentage. Also, samples were cured for 7
days and 28 days before applying swell tests. Curing of samples affects swell
percentages and rate of swell in positive way.
7
Shuai, Fangsheng. "Simulation of swelling pressure measurements on expansive soils." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24015.pdf.
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De, Sousa Vinagre Tiberio J. V., and Sousa Vinagre Tiberio J. V. De. "Expansive and collapsing behaviour of volume change soils." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/23594.
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This thesis is designed to achieve three goals: Goal One - to introduce the reader to soils exhibiting expansive and/or collapsing behaviour; Goal Two - to provide an in depth understanding of aspects of this behaviour, obtained from an extensive study of these soil types; and, Goal Three - to serve as a reference for future research work (a recommendation for further research proposed in Chapter Ten of this thesis). The thesis is divided in two main parts. In the first part representative soil types were selected on the basis of their properties and expected engineering behaviour. The soil structure and clay minerals were also studied in part one of this thesis. The second part of the thesis deals with aspects of expansive and collapsing behaviour of soils. Chapter three provides the introduction to the subsequent chapters on expansive and collapsing behaviour of volume change soils.
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Habibbeygi, Farzad. "Experimental Study on the Behaviour of Expansive Soils." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/75688.
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In this research, laboratory-based experiments were conducted to investigate the volumetric and mechanical behaviour of expansive soils. The effects of clay mineralogy, initial water content and preconsolidation stress on the compressibility and shear strength of expansive clays were investigated. Predictive models based on regression analysis and artificial neural networks are proposed to estimate the compression and shear behaviour of expansive soils. Additionally, a green stabiliser was introduced to reduce the swell potential of expansive clays.
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Byiringiro, Alfred. "Effect of paper mill ash on properties of expansive soils." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86287.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Expansive soils, one of the problematic soils, are encountered on all continents with exception of polar continents. Problems caused by their heaving and shrinking behaviour, particularly to light structures, have been reported from different countries to place large financial burden on developers. For this reason, many techniques have been developed and applied to prevent and/or remediate the damage caused by these soils. Soil stabilization with traditional chemical additives has been applied successfully since ancient times. In addition to traditional additives such as lime, cement, fly ash, etc., some non-traditional additives, such as polymer based products, salts, etc. have been used effectively for soil treatment. On the other hand, industries are increasingly challenged by waste management in an acceptable and environmentally friendly manner. In this regard, a number of researches have been done on using industrial waste for soil improvement purposes. The study and understanding of basic reactions involved in lime-soil stabilization persuaded many researchers to study the applicability of lime-rich products for soil treatment. Studies conducted by Khalid et al. (2012); Muchizuki et al. (2004) and Thacker (2012) showed that lime-rich products such as pulp fly and bottom ashes and CaO by-products, can be applied for soil stabilization. This research was thus performed to investigate the effect of lime-rich paper mill waste ash on expansive soil properties. Two commonly listed soil engineering properties namely volume change and strength were investigated. Soil strength was examined in terms of unconfined compressive strength (UCS), due to its correlations with a number of other soil properties, and the volume change in terms of free swell and swelling pressure. In addition to these two engineering properties, dry density and moisture content were also studied due to their involvement in structural design, as well as gradation, Atterberg limits and California Bearing Ratio (CBR). The choice of these properties was also influenced by the availability of a standard (ASTM D4609-08) specifically developed to assess the effectiveness of admixtures for soil stabilization. Two main types of materials were used namely three clay materials and paper mill ash. According to the index properties, commonly used for expansive soil classification, three clays were classified into low, medium and high degrees of potential expansiveness. The ash results from the combustion of paper mill sludge, sawdust, bark, coal ash and bituminous coal in a multi-fuel boiler for the purpose of electricity and steam production. The tests mentioned above were conducted on both untreated and treated clays and the results were compared. Since the study was carried out on this material based on the fact that it contains lime, the procedure applied for lime-soil stabilization was considered. In general, it was observed that ash-soil treatment has a number of effects similar to lime-treatment and almost all studied properties were enhanced for all clays. It can thus be concluded that the paper mill ash from a multi-fuel boiler can be efficiently used for expansive soil treatment. For optimum use of this material for expansive soil treatment, more tests and further researches have been recommended.
AFRIKAANSE OPSOMMING: Uitsettende gronde, een van die probleemtipe-gronde, kom op alle kontinente voor, behalwe die twee poolkontinente. Probleme veroorsaak deur uitswellende en inkrimpende gedrag van hierdie gronde, veral finansiële onkostes van ligte strukture is al in baie lande aangemeld. Vir hierdie rede is baie tegnieke ontwikkel en toegepas om skade wat deur hierdie tipe gronde veroorsaak is, te voorkom en/of herstel. Hierdie tegnieke sluit grondstabilisasie met chemiese bymengsels in, veral tradisionele bymengsels, wat met groot sukses in die verre verlede toegepas en na moderne tye oorgedra is. Bykomend tot tradisionele bymengsels soos kalk, sement, vlieg-as ensovoorts is ʼn aantal nie-tradisionele bymiddels soos polimeergebaseerde produkte, soute en ander produkte ontwikkel vir grondstabilisasie. Aan die ander kant raak industrieë toenemend daarmee gemoeid om afvalstowwe op ʼn aanvaarbare en omgewingsvriendelike wyse te bestuur. Op hierdie gebied is ʼn aantal navorsingsprojekte al uitgevoer om industriële afval vir grondverbetering te gebruik en sodoende die las op nywerhede te verlig. Navorsing is onderneem om die basiese reaksies wat onstaan tydens stabilisasie van grond met tradisionele en moderne middels te bepaal en om die geskiktheid van kalkryke produkte vir grondstabilisasie te ondersoek. Baie navorsing is uitgevoer wat aangetoon het dat kalkhoudende produkte soos pulp vlieg- en oondresidu-as, asook CaO neweprodukte gebruik kan word vir stabilisasie. Gebaseer hierop is hierdie projek onderneem om die effek van papiermeulas, verkry deur die verbranding in ʼn veelvuldige brandstof-stoomketel, op die gedrag van uitsettende grond te ondersoek. Tydens hierdie studie is twee algemene ingenieurseienskappe van grond, naamlik sterkte en volumeverandering ondersoek. Grondsterkte is geëvalueer in terme van eenassige druksterkte (EDS) as gevolg van ? deur middel van die korrelasie met ʼn aantal ander grondeienskappe, en die volumeverandering in terme van vry-swel en sweldruk. Addisioneel tot hierdie twee grondeienskappe is droë digtheid en waterinhoud ook bestudeer aangesien beide in struktuurontwerp betrokke is. Verdere eienskappe wat ondersoek is, is gradering, Atterberggrense en Kaliforniese drakragverhouding (KDV). Die keuse van hierdie eienskappe is beïnvloed deur die beskikbaarheid van ʼn toetsstandaard (ASTM D4609-08) wat spesifiek ontwikkel is om die effektiwiteit van bymengsels vir grondstabilisasie te evalueer. Hierdie standaard is deurgaans as verwysing tydens die projek gebruik. Daar is waargeneem dat as-behandeling van grond ʼn aantal effekte het soortgelyk aan kalkbehandeling, met die uitsondering van die droë digtheid en optimum waterinhoud van een van die gronde wat getoets is. Byna al die eienskappe wat ondersoek is, soos EDS, KDV, ensovoorts, is verbeter behalwe in die geval van die eerste klei waarvan die plastisiteitsindeks verhoog het en die grond meer plasties geraak het. Daar kan dus afgelei word dat papiermeule-as vanaf ʼn stoomketel wat veelvuldige tipes brandstof gebruik geskik is vir die behandeling van uitsettende grond. Om die optimumgebruik van hierdie materiaal vir die stabilisasie van swellende klei te bepaal, is meer toetse en projekte nodig.
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Burgoon, Justin Eugene. "Post-tensioned ribbed mat foundations on highly expansive soils." Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/498.
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Sapkota, Binod Kumar. "Soil/pavement interaction for pavements on expansive soil." Thesis, Queensland University of Technology, 1994.
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Brooks, Mark Whitfield 1964. "Distribution and assessment of expansive clay soils in the Tucson Basin, Arizona." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276976.
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Expansive soils contain clay minerals that undergo a change in bulk volume in response to variances in environmental conditions. The ability to predict the occurrence and geotechnical behavior of swelling soils with a known degree of certitude would allow engineers to take measures to limit the damage resulting from these metastable soils. Research was conducted to investigate the regional distribution, mineralogy, and engineering properties of expansive soils in the Tucson Basin. Mineralogic studies employed X-ray diffraction procedures for the identification of clay mineralogy. The compilation of expansion-related soil parameters, from the geotechnical job-files of a local engineering consulting firm, allowed the development of an engineering database. The application of geostatistical analysis for the cartographical representation of mineralogic and geotechnical data permitted a regional characterization of expansive clay soils. Clay mineralogy was found to be directly related to the volumetric stability displayed by native soils, as well as the geology of the Tucson Basin.
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Zhan, Liangtong. "Field and laboratory study of an unsaturated expansive soil associated with rain-induced slope instability /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202003%20ZHAN.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 471-490). Also available in electronic version. Access restricted to campus users.
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Lucian, Charles. "Geotechnical Aspects of Buildings on Expansive Soils in Kibaha, Tanzania : Preliminary Study." Licentiate thesis, Stockholm : Division of soil and rock mechanics, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4056.
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Zhang, Xiong. "Consolidation theories for saturated-unsaturated soils and numerical simulation of residential buildings on expansive soils." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2747.
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The coupled and uncoupled consolidation theories for saturated-unsaturated soils have been discussed. A new method for constructing the constitutive surfaces for saturated-unsaturated soils has been proposed. The consolidation processes for saturated-unsaturated soils have been explained by thermodynamic analogue. One dimensional consolidation theory for saturated-unsaturated soils is presented and a new method is proposed to calculate the immediate settlement, total settlement and the time history of the consolidation settlement manually in the same way as what we have done for saturated soils with a higher accuracy. It makes the consolidation theory of unsaturated soils as applicable as that of saturated soils. This method can also be used to perform uncoupled two or three dimensional consolidation calculation for both expansive soils and collapsible soils. From the analysis, the equivalent effective stress and excessive pore water pressure can be easily calculated. At the same time, the physical meanings for the parameters in the constitutive laws for saturated-unsaturated are illustrated. A new set of the differential equations for the coupled two or three dimensional consolidation of saturated-unsaturated soils are proposed, together with the corresponding method to solve the differential equations. It is also proved numerically and analytically that during the consolidation process the Mandel-Cryer effect exists for unsaturated expansive soils and there is a ??reverse?? Mandel-Cryer effect for unsaturated collapsible soils. A new method is proposed to estimate the volume change of expansive soils.
A complete system is proposed for the numerical simulation of residential buildings on expansive soils. The strength of this method lies in its use of simple and readily available historic weather data such as daily temperature, solar radiation, relative humidity, wind speed and rainfall as input. Accurate three dimensional predictions are obtained by integrating a number of different analytical and numerical techniques: different simulation methods for different boundary conditions such as tree, grass, and bare soils, coupled hydro-mechanical stress analysis to describe deformation of saturated-unsaturated soils, jointed elements simulation of soil-structure interaction, analysis of structure stress moment by general shell elements, and to assess structural damage by the smeared cracking model. The real-time and dynamic simulation results are consistent with filed measurements.
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Cetiner, Sertan Isik. "Stabilization Of Expansive Soils By Cayirhan Fly Ash And Desulphogypsum." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1119387/index.pdf.
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Expansive soils are one of the most serious problems which the foundation
engineer faces. Several attempts are being made to control the swell-shrink
behavior of these soils. One of the most effective and economical methods is to use
chemical additives. Fly ash and desulphogypsum, both of which are by-products of
coal burning thermal power plants, are accumulating in large quantities all over the
world and pose serious environmental problems. In this study, the expansive soil
was stabilized using the fly ash and desulphogypsum obtained from Çayirhan Thermal Power Plant. Fly ash and desulphogypsum were added to the expansive soil from 0 to 30 percent. Lime was used to see how efficient fly ash and desulphogypsum on expansive soil stabilization were, and was added to the expansive soil from 0 to 8 percent. The properties obtained were chemical composition, grain size distribution, consistency limits, swelling percentage, and rate of swell. Fly ash, desulphogypsum, and lime added samples were cured for 7 days and 28 days, after which they were subjected to free swell tests. Swelling percentage decreased and rate of swell increased with increasing stabilizer percentage. Curing resulted in further reduction in swelling percentage and further increase in rate of swell. 25 percent and 30 percent fly ash and desulphogypsum additions reduced the swelling percentage to levels comparable to lime stabilization.
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Demirbas, Gunes. "Stabilization Of Expansive Soils Using Bigadic Zeolite (boron By-product)." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610671/index.pdf.
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Expansive soils are a worldwide problem that poses several challenges for civil
engineers. Such soils swell when given an access to water and shrink when they
dry out. The most common and economical method for stabilizing these soils is
using admixtures that prevent volume changes. In this study the effect of using
Bigadic zeolite (boron by-product) in reducing the swelling potential is examined.
The expansive soil is prepared in the laboratory by mixturing kaolinite and
bentonite. Bigadic zeolite (boron by-product) is added to the soil at 0 to 25 percent
by weight. Grain size distribution, Atterberg limits and swell percent and rate of
swell of the mixtures are determined. Specimens are cured for 7 and 28 days. As a
result of the experimental study, it was seen that addition of Bigadic zeolite (boronby-product) decreased swelling potential and rate of swell of the artificially
prepared expansive soil specimen at laboratory conditions. The swell percentage
and rate of swell of the stabilized specimens are affected positively by curing.
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Hong, Gyeong Taek. "Earth pressures and deformations in civil infrastructure in expansive soils." Texas A&M University, 2008. http://hdl.handle.net/1969.1/85916.
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This dissertation includes the three major parts of the study: volume change, and lateral
earth pressure due to suction change in expansive clay soils, and design of civil
infrastructure drilled pier, retaining wall and pavement in expansive soils.
The volume change model in expansive clay has been refined to reinforce
realistic characteristics of swelling and shrinkage behavior of expansive clay soils.
Refinements include more realistic design soil suction versus depth profiles and
improved characterizations of the effects of soil cracking, overburden stress, and lateral
earth pressure. The refined model also includes an algorithm of assigning suctionvolumetric
water content curves and diffusivity through the soil.
The typical lateral earth pressure distribution during wetting against a stationary
wall is proposed. The proposed stationary retaining wall-soil system in expansive soils
includes an upper movement active zone and a lower anchor zone. Mohrâ s circles and
failure envelopes are used to define the effective horizontal stress and shear failure in an
unsaturated soil. The prediction of the horizontal pressures due to suction change in a
soil is compared with the in situ measurement of natural horizontal pressures and the
measurements from the large scale tests. It is found that agreement between the
measured and predicted horizontal pressures is satisfactory. Case studies of axial and
bending of the pier are presented with both uniform and non-uniform wetting. The pier case study for axial behavior shows a good agreement with a heave at ground surface
and uplift forces. Three case studies for bending behavior of the pier and retaining wall
are presented based on suction change.
Pavement design program has been refined to extend the design capabilities into
both flexible and rigid pavements supported by pavement treatments. The comparative
case studies using both current and new methods in pavement design show that the
current method criterion of 1-inch is unnecessarily conservative. Furthermore, the
current method does not provide a means of anticipating subgrade shrinkage that will
result in longitudinal cracking along the edge of the pavement. The design calculations
with both methods lead to the conclusion that neither the swelling movement, as in the
current method, nor the total movement, as in the new method, is a reliable indicator of
likely acceptable pavement performance. Instead, all of these case studies show that it is
important to use the predicted history of the present serviceability index and the
international roughness index as the proper design guideline for an acceptable treatment
of the subgrade of an expansive soil.
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Lucian, Charles. "Geotechnical Aspects of Buildings on Expansive Soils in Kibaha, Tanzania." Doctoral thesis, KTH, Jord- och bergmekanik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9244.
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The focus of this study is on potential damages to buildings resulting from expansive soils in Tanzania, particularly clay soils in Kibaha. For the fact that most of the affected structures are founded on expansive soils, a clear understanding of the behaviour of soils and their interaction with structures has been of interest to the study in order to evaluate properly the source of the problem.The geotechnical behaviour of expansive clay soils is investigated by looking into the geomorphologic, geological and climatic conditions and mineralogical composition of the soils in the study area.Two sites, representative of known problem-areas in Kibaha were selected for geotechnical tests. Geotechnical site investigation consisted of open trial pits, profile description and the collection of both disturbed and undisturbed samples. To extend and amplify the findings, supplementary samples were collected from the environs of the two sites.The collected samples were submitted to soil laboratories at KTH, ARU, SEAMIC and DIT for mineralogical composition tests, natural water content, density, Atterberg limits and swell tests. The results of this investigation indicate that soils in Kibaha contains clay (31%), have high liquid limit (59%) and plastic limit (37%) which indicate high potential swell.Since swell pressure, free swell and swell percent are key properties of expansive soils, the swell properties were measured by free swell tests and one-dimensional oedometer swell tests. The free swell ranged from 100% to 150% and the swell pressure was in the region of 45 kPa. The coefficient of linear extensibility (COLE) was determined for characterizing expansive clays. For all tested samples, COLE ranged from 0.09 to 0.14 indicating that soils fall in the region of high to very high expansion potential rating. The properties of expansive soils were confirmed by the x-ray diffraction test which showed the presence of smectite in the soil. Furthermore, total suction measurement technique using filter paper method indicated that the soils have high suction values, signifying that they have a tendency to swell upon wetting depending on plasticity of particular soil.The depth of the active zone was measured as a function of moisture variations in the profiles during two extreme weather conditions. The active zone depth was found to be between 1.0 and 2.0 m deep. Procedures to assess models to predict swell in the case study were outlined together with their validity.Vertical and horizontal spatial variability in selected soil properties was defined using geostatistical techniques through the fitting of variogram. The indicator semivariograms of both clay contents and free swell gave a range of 20 m horizontally and 1.0 m vertically, with the horizontal variograms exhibiting greater ranges than the dipping variograms.Physical conditions of the surveyed properties in the area confirmed that building damages are associated with poor building materials triggered by expansive soils. In support of the obtained data, the actual behaviour of the foundations was supplemented with prototypes of strip foundations whose performances were monitored over a period of four months. Finally, suggested are the ways forward to solve the problem of foundation on expansive soilQC 20100824
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Lucian, Charles. "Geotechnical aspects of building on expansive soils in Kibaha, Tanzania /." Stockholm : Arkitektur och samhällsbyggnad, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9244.
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Qi, Shunchao. "Numerical Investigation for Slope Stability of Expansive Soils and Large Strain Consolidation of Soft Soils." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/37019.
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Several geotechnical processes can only be reliably interpreted by taking account of the soil-atmosphere interactions. This thesis investigates two geotechnical problems involving soil-atmosphere interactions that drive water flow through the soil skeleton in two opposite directions; Problem 1: slope failure in expansive soils induced by water infiltration, Problem 2: large strain consolidation of soft soils induced by water evaporation. Both problems are of practical interest for safe and economical design of various geotechnical infrastructures. Two major geotechnical activities in the world; namely, the construction of water transfer canal in expansive soil area in China and the deposition of oil sands and hard rock tailings in Canada can be cited as classic examples of Problems 1 and 2, respectively. In such problems, substantial zones of the domain may switch between an unsaturated and saturated condition. Therefore, rational analysis requires simultaneous modelling of both unsaturated and saturated soil behaviour.
The first goal of this thesis is to investigate the influence of swelling (the most characteristic behaviour of expansive soils) on slope stability using numerical methods. Swelling of expansive soils contributes to slope instability during rainfall because of two key reasons (i) soil swelling affects the flow process that actually induces swelling, (i.e. a typical coupling phenomenon), and (ii) swelling-induced stress redistribution and displacement development. In this thesis, the first effect is studied by a coupled (mechanical-hydraulic) numerical analysis of the response of a slope to rainfall using commercial software (GeoSlope). The second effect, the swelling-induced stress redistribution and displacement development after wetting, is tracked using a newly developed numerical program. In the program strain softening behaviour is introduced into the elasto-plastic Mohr-Coulomb Model for modelling unsaturated soil. A novel stress (net stress and suction)-dependent model for moduli of elasticity, combined with the predictive model for shear strength based on Soil Water Retention Behaviour are incorporated into the numerical program to achieve a smooth transition between saturated and unsaturated states. The results show that soil swelling can decrease the factor of safety by accelerating the wetting front depth due to hydro-mechanical coupling, while changes of sliding mass geometry has a negligible influence. The change of stress regime associated with soil swelling is significant to induce plastic strain softening (swelling-induced softening) and contribute to the slope failures.
The second goal of thesis is to develop a novel computer program for simulation of large strain consolidation of soft soil under both self-weight and evaporation conditions. This program is both theoretically sound and practically applicable. Several basic/advanced constitutive models for unsaturated soils, including State Surface Model (SSM), Barcelona Basic model (BBM), Glasgow Coupled model (GCM) and bounding surface water retention model, are innovatively implemented into a piece-wise linear framework solved using finite difference technique. The developed program is referred to as UNSATCON-(ML), which has been tested using (a) existing analytical/numerical solutions and (b) various laboratory and field studies for single-layer and multiple-layer deposition of hard rock and oil sands tailings. Features of UNSATCON-(ML) that are improvements over existing models typically used to analyze consolidation-desiccation in soft soils include: (i) coupling of soil large deformation with true unsaturated water flow; (ii) correct reproduction of the shrinkage behaviour of soil under evaporation-induced desiccation; (iii) smooth transition between saturated and unsaturated states despite that some selected models are established using two independent stress variables, (iv) ensuring strictly mass conservation of water, and (v) simulation of irrecoverable volume change and hydraulic hysteresis to properly analyze multilayer tailings deposition. A number of hypothetical field case analyses are carried out using UNSATCON-ML, illustrating its applicability to industry.
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Wayllace, Alexandra Likos William J. "Volume change and swelling pressure of expansive clay in the crystalline swelling regime." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/7110.
Full textAbstract:
Title from PDF of title page (University of Missouri--Columbia, viewed on March 2, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. William Likos, Thesis Supervisor. Vita. Includes bibliographical references.
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Henderson, Susan J. "Expansive soil/footing systems incorporating compressible void formers." Thesis, Queensland University of Technology, 1988. https://eprints.qut.edu.au/36466/1/36466_Henderson_1988.pdf.
Full textAbstract:
Paper-derived void formers for footings have changed
little since they were developed nearly three decades
ago, when practical understanding of the behaviour of
expansive clays and consequent soil-structure
interaction was just emerging. In this thesis, current
understanding and analytical techniques are applied to
investigate the performance of pier-and-beam footings
incorporating void formers.
Published soil
supplemented by a
suction data were collated
program of sampling below slabs
and
to
provide soil moisture conditions, before
construe .~ion, typical of the semi-arid
central-southeast Queensland.
and after
regions of
A laboratory test was developed to evaluate the void
formers' resistance to concentrated loadings, such as
could occur during construction. A suction-water
content relationship was used to control moisture in a
second test which investigated load-compression
behaviour of the void formers at expected in-service
conditions.
One product was characteristed as the basis of a finite
element model to demonstrate the interaction of
pressures and movements as the soil wets up and heaves,
and to investigate the relative effects of various void
former properties.
It was shown that the void formers' peak strength at
in-service moisture conditions and ease of moisture
absorption are critical to the magnitude of uplift
pressure transmitted to the slab and that the present
design assumption of zero uplift pressure is
inappropriate.
25
Yesilbas, Gulsah. "Stabilization Of Expansive Soils By Using Aggregate Waste, Rock Powder And Lime." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604950/index.pdf.
Full textAbstract:
Expansive soils are a worldwide problem that poses several challenges for civil engineers. Such soils swell when given an access to water and shrink when they dry out. The most common and economical method for stabilizing these soils is using admixtures that prevent volume changes. In this study the effect of using rock powder and aggregate waste with lime in reducing the swelling potential is examined. The expansive soil used in this study is prepared in the laboratory by mixturing kaolinite and bentonite. Lime was added to the soil at 0 to 9 percent by weight. Aggregate waste and rock powder were added to the soil at 0 to 25 percent by weight. Grain size distribution, Atterberg limits and swell percent and rate of swell of the mixtures were determined. Specimens were cured for 7 and 28 days. This method of treatment caused a reduction in the swelling potential and the reduction was increased with increasing percent stabilizers.
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Liu, Yunlong. "Interpretation of Load Transfer Mechanism for Piles in Unsaturated Expansive Soils." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38804.
Full textAbstract:
Water infiltration associated with natural precipitation events or other artificial activities such as pipe leaks in expansive soils significantly influence the engineering properties; namely, coefficient of permeability, shear strength and volume change behavior. For this reason, it is challenging to design or construct geotechnical infrastructure within or with expansive soils. Several billions of dollars losses, world-wide, can be attributed to the repairing, redesigning and retrofitting of infrastructure constructed with or within expansive soils, annually. Piles are widely used as foundations in expansive soils extending conventional design procedures based on the principles of saturated soil mechanics. However, the behavior of piles in unsaturated expansive soils is significantly different from conventional non-expansive saturated soils. Three significant changes arise as water infiltrates into expansive soil around the pile. Firstly, soil volume expansion contributes to ground heave in vertical direction. Secondly, volume expansion restriction leads to development of the lateral swelling pressure resulting in an increment in the lateral earth pressure in the horizontal direction. Thirdly, pile-soil interface shear strength properties change due to variations in water content (matric suction) of the surrounding soil. These three changes are closely related to matric suction variations that arise during the water infiltration process. For this reason, a rational methodology is necessary for the pile load transfer mechanism analysis based on the mechanics of unsaturated soils.
Studies presented in this thesis are directed towards developing simple methods to predict the load transfer mechanism changes of piles in expansive soils upon infiltration. More emphasis is directed towards the prediction of the pile mechanical behavior which includes the pile head load-displacement relationship, the pile axial force (shaft friction) distribution and the pile base resistance using unsaturated mechanical as a tool. The function of matric suction as an independent stress state variable on the mechanical behavior pile is highlighted. More specifically, following studies were conducted:
(i) Previous studies on various factors influencing the load transfer mechanisms of piles in unsaturated expansive soils are summarized and discussed to give a background of current research. More specifically, state-of-the-art reviews are summarized on the application of piles in expansive soils, mobilization of lateral swelling pressure, mobilization of unsaturated pile-soil interface shear strength and methods available for the load transfer analysis of piles in expansive soils.
(ii) Employing unsaturated soil mechanics as a tool, theoretical methods are proposed for estimating the lateral earth pressure variations considering the mobilization of lateral swelling pressure. The proposed methods are verified using two large-scale laboratory studies and two field studies from published literatures.
(iii) The shear displacement method and load transfer curve methods used traditionally for pile load transfer mechanisms analysis for saturated soils were modified to extend their applications for unsaturated expansive soils. The influence of volume change characteristics and unsaturated soil properties on unsaturated expansive soils are considered in these methods. The validation of the modified shear displacement method and modified load transfer curve method were established using a large-scale model test performed in the geotechnical engineering lab of University of Ottawa and a field case study results from the published literature.
(iv) A large-scale model pile infiltration test conducted in a typical expansive soil from Regina in Canada in the geotechnical lab of University of Ottawa is presented and interpreted using the experimental data of volumetric water content suction measurements and shear strength data. The results of the comprehensive experiment studies are also used to validate the proposed modified shear displacement method and modified load transfer curve method achieving reasonable good comparisons.
The proposed modified shear displacement method and modified load transfer curve method are simple and require limited number soil properties including the soil water characteristic curve (SWCC), matric suction profile upon wetting and drying and some soil physical properties. Due to these advantages, they can be easily and conveniently applied in engineering practice for prediction of the mechanical behavior of piles in unsaturated expansive soils, which facilitate practicing engineers to produce sound design of pile foundation in unsaturated expansive soils in a simplistic manner.
27
Long, Xiaoyan. "Prediction of shear strength and vertical movement due to moisture diffusion through expansive soils." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4313.
Full textAbstract:
This dissertation presents an investigation of engineering behavior of expansive
soils. An analytical study was undertaken for the development and modification of a
Windows-based two-dimensional finite element computer program FLODEF that
performs a sequentially coupled flow-displacement analysis for the prediction of
moisture diffusion and the induced volume change in soils supporting various elements
of civil infrastructure. The capabilities of the model are illustrated through case studies
of shear strength envelope forecast and parametric studies of transient flow-deformation
prediction in highway project sites to evaluate the effectiveness of engineering treatment
methods to control swell-shrink deformations beneath highway pavements. Numerical
simulations have been performed to study the field moisture diffusivity using a
conceptual model of moisture diffusion in a fractured soil mass. A rough correlation
between field and the laboratory measurements of moisture diffusion coefficients has
been presented for different crack depth patterns.
28
Hergul, Timucin. "An Experimental Study On The Treatment Of Expansive Soils By Granular Materials." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614886/index.pdf.
Full textAbstract:
Expansive soils are a worldwide problem that possesses various challenges for civil engineers. With increasing water content, they exhibit excessive volume changes, resulting in large horizontal and vertical stresses to the structures located or buried in these regions. The most common method to minimize this effect is to replace these types of clays around the proposed structure with nonexpansive soils. For the cases needing larger volume of replacement, either sidewalls or the foundations must be designed to cater for the anticipated pressures or a suitable improvement technique shall be applied in place.
In this experimental study, it is intended to investigate the possible positive effects of trenches backfilled with granular material such as crushed stone or rock on the improvement of swell parameters of expansive soils. Thin-wall oedometer tests, conventional oedometer tests and larger size tests with moulds were performed on artificially compacted untreated and granular fill treated samples for this purpose. The trenches were modeled by opening a hole with a diameter that satisfies the predicted percent trench content at the center of the soil samples, which was then backfilled with granular material. Modified thin-wall oedometer tests were performed to measure the lateral swell pressures of both untreated and treated samples, whereas the conventional oedometer tests and tests on samples placed in moulds were performed to measure the vertical swell parameters of soils. It was observed that both the vertical swell percentages as well as the lateral swell pressures reduced considerably as the volume of granular material filled trench was increased. The treatment was observed to be more remarkable under the surcharge effect of a light weight structure or a fill placed on top.
29
Ika, Putra Agus. "Stabilisation of expansive subgrade soils with slag and cement for road construction." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/374.
Full textAbstract:
This research evaluates stabilisation of expansive soil as a subgrade for road pavement. The recommended stabiliser proportion was 13.5% slag + 1.5% cement at 28 days curing time, which based on obtaining UCS test results that eight times magnitudes higher than the strength of the non-stabilised soil. The CBR values were more than four times higher than the minimum required for designing road pavement. The best resilient modulus correlation model was the hyperbolic correlation model.
30
Mansour, Eman M. S. "Swell Pressures and Retaining Wall Design in Expansıve Soils." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1323536478.
Full text
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Gomes, Ribamar de Jesus. "Estudo geotecnico de um solo superficial da cidade de Bragança Paulista - SP." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258204.
Full textAbstract:
Orientador: David de CarvalhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Estuda-se o comportamento geotécnico de um perfil de solo tropical típico da região de Bragança Paulista - SP. Esse perfil é classificado pela pedologia como um Latossolo Vermelho Amarelo. Para atingir esse objetivo foram realizados ensaios de caracterização, ensaios triaxiais e ensaios edométricos no teor de umidade natural e saturado. Nos ensaios de caracterização constatou-se o comportamento laterítico do solo. Nos ensaios edométricos quando os corpos de prova foram inundados nas tensões normalmente adotadas em projetos de fundações de edificações de pequeno e médio porte, construções características da cidade, constatou -se indícios de expansibilidade e colapsibilidade, apontando para a necessidade de estudos mais aprofundados sobre esses fenômenos em outras localidades do município
Abstract: The survey has the objective to investigate the geotechnical behavior of a typical soil profile at Bragança Paulista city - São Paulo State - Brazil. This profile is classified by the pedology as Red Yellow Oxisoil. To achieve this aim were accomplished characterization geotechnical tests, triaxial tests and consolidation tests. In the characterization tests was proved the lateritic behavior of the soil. In the consolidation tests when the samples were saturated in the tensions normally stipulated in edifications foundations projects at small and medium conveyance the results had pointed colapsible and expansive soil existence at the referred city
Mestrado
Geotecnia
Mestre em Engenharia Civil
32
Guo, Jiaying. "Framework of Estimation of the Lateral Earth Pressure on Retaining Structures with Expansive and Non-expansive Soils as Backfill Material Considering the Influence of Environmental Factors." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34858.
Full textAbstract:
Lateral earth pressures (LEP) that arise due to backfill on retaining structures are typically determined by extending the principles of saturated soil mechanics. However, there is evidence in the literature to highlight the LEP on retaining structures due to the influence of soil backfill in saturated and unsaturated conditions are significantly different. Some studies are reported in the literature to interpret the variation of LEP on the retaining structures assuming that the variation of matric suction in unsaturated backfill material is hydrostatic (i.e. matric suction is assumed to decrease linearly from the surface to a value of zero at the ground water table). Such an assumption however is not reliable when the backfill behind the retaining wall is an expansive soil, which is extremely sensitive to the changes in variation of water content values. Significant volume changes occur in expansive soils due to the influence of environmental factors such as the infiltration and evaporation. In addition to the volume changes, the swelling pressure of the expansive soils also varies with changes in water content and can significantly influence the LEPs behind the retaining wall.
In this thesis, a framework for estimating the LEPs of unsaturated soils is proposed considering the variation of matric suction with respect to various water flow rates (i.e. infiltration and evaporation). The proposed approach is extended for expansive and non-expansive soils in this thesis taking into account of the influence of both the cracks and the lateral swelling pressure with changes in water content. A program code LEENES (Lateral pressure estimation on retaining walls taking account of Environmental factors for Expansive and Non-Expansive Soils) in MATLAB is written to predict the LEP. The program LEENES is valuable tool for geotechnical engineers to estimate the LEPs on retaining structures for various scenarios that are conventionally encountered in geotechnical engineering practice. The studies presented in this thesis are of interest to the practitioners who routinely design retaining walls with both expansive and non-expansive soils as backfill material.
33
Lu, Lu. "A simple technique for estimating the one-dimensional heave of natural expansive soils." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28750.
Full textAbstract:
Expansive soils are considered to be a nightmare to the geotechnical engineers. As the losses to the infrastructure constructed on expansive soils is estimated to be in billions of dollars world wide annually, several researchers and practitioners from various regions of the world have made significant contributions to better our present understanding of these problematic soils. One of the topics that attracted interest is related to the 1-D heave prediction or estimation methods for expansive soils. Early research studies on this topic were focused on developing empirical relationships which are not universally valid. Current techniques use soil suction methods and oedometer test methods to predict or estimate the 1-D heave; however, the various soil parameters required in these techniques can only be obtained from time consuming laboratory or in-situ tests that are expensive and difficult to be performed by conventional geotechnical engineers.
In the present study, a simple technique is proposed to estimate the 1-D heave in expansive soils which requires only the information of plasticity index, Ip and variation in water content with respect to depth in the active zone. This technique is developed using the results of 5 case studies published in the literature. In addition to these case studies, 8 other case studies results of 1-D heave in expansive soils are summarized. The data of 13 of the case studies is collected from various regions of the world which include Australia, Canada, Chile, Saudi Arabia, Sudan, United States and Yugoslavia. Comparisons are provided between the measured and estimated 1-D heave for all the case studies have been using the proposed simple technique. There is a reasonably good comparison between the measured heave and the estimated heave for 8 of the 13 case studies results (i.e., less than 30%). The estimated heave is more than the measured heave for all the case studies; which is conservative from an engineering practice perspective. The reasons associated with the discrepancies between the measured and predicted 1-D heave values for the remainder of the five case studies are also discussed.
The proposed simple technique is encouraging for the practicing geotechnical engineers in the estimation of 1-D heave in expansive soils.
34
Cleall, Peter John. "An investigation of the thermo/hydraulic/mechanical behaviour of unsaturated soils, including expansive clays." Thesis, Cardiff University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389795.
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Adem, Hana Hussin. "Modulus of Elasticity Based Method for Estimating the Vertical Movement of Natural Unsaturated Expansive Soils." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31910.
Full textAbstract:
Expansive soils are widely distributed in arid and semi-arid regions around the world and are typically found in a state of unsaturated condition. These soils are constituted of the clay mineral montmorillonite that is highly active and contributes significantly to volume changes of soils due to variations in the natural water content conditions. The volume changes of expansive soils often cause damage to lightly loaded structures. The costs associated with the damage to lightly loaded structures constructed on expansive soils in the United States alone were estimated as $2.3 billion per year in 1973, which increased to $13 billion per year by 2009. In other words, these damages have increased more than five fold during the last four decades. Similar trends in damages were also reported in other countries (e.g., Australia, China, France, Saudi Arabia, United Kingdom, etc.).
Numerous methods have been proposed in the literature over the past 50 years for the prediction of the volume change movement of expansive soils. However, the focus of these methods has been towards estimating the maximum potential heave, which occurs when soils attain the saturation condition. The results of heave estimation considering saturated soil conditions are not always useful in engineering practice. This is because most of damages due to expansive soils often occur prior to reaching the saturation condition. A reliable design of structures on expansive soils is likely if the anticipated soil movements in the field can be reliably estimated over time, taking into account the influence of environmental factors. Limited studies are reported in the literature during the past decade in this direction to estimate/predict the expansive soil movements over time. The existing methods, however, suffer from the need to run expensive and time consuming tests. In addition, verification of these studies for different natural expansive soils has been rather limited.
A simple approach, which is referred to as a modulus of elasticity based method (MEBM), is proposed in this study for the prediction of the heave/shrinkage movements of natural expansive soils over time. The proposed MEBM is based on a simplified constitutive relationship used for the first time to estimate the vertical soil movements with respect to time in terms of the matric suction variations and the corresponding values of the modulus of elasticity. The finite element program VADOSE/W (Geo-Slope 2007) for simulating the soil-atmospheric interactions is used as a tool to estimate the changes in matric suction over time. A semi-empirical model that was originally proposed by Vanapalli and Oh (2010) for fine-grained soils has been investigated and extended for unsaturated expansive soils to estimate the variation of the modulus of elasticity with respect to matric suction in the constitutive relationship of the proposed method. The MEBM has been tested for its validity in five case studies from the literature for a wide variety of site and environmental conditions, from Canada, China, and the United States. For each case study, factors influencing the volume change behavior of soils, such as climate conditions, soil cracks, lawn irrigation, and cover type (pavement, vegetation), are successfully modeled over the period of each simulation. The proposed MEBM provides good predictions of soil movements with respect to time for all the case studies. The MEBM is simple and efficient for the prediction of vertical movements of natural expansive soils underlying lightly loaded structures.
In addition, a new dimensionless model is also proposed, based on the dimensional analysis approach, for the estimation of the modulus of elasticity which can also be used in the constitutive relationship of the MEBM. The dimensional model is rigorous and takes into account the most significant influencing parameters such as matric suction, net confining stress, initial void ratio, and degree of saturation. This model provides a comprehensive characterization of the modulus of elasticity of expansive soils under unsaturated conditions for different scenarios of loading conditions (i.e., both lightly and heavily loaded structures).
The results of the present study are encouraging for proposing guidelines based on further investigations and research studies for the rational design of pavements, shallow and deep foundations placed on/in expansive soils using the mechanics of unsaturated soils.
36
Osman, Norhaslinda Yasmin, and n/a. "The development of a predictive damage condition model of light structures on expansive soils using hybrid artificial intelligence techniques." Swinburne University of Technology, 2007. http://adt.lib.swin.edu.au./public/adt-VSWT20071002.131831.
Full textAbstract:
Expansive soils have damage light structures due to movement of soil which was a common problem all around the world. Soils exhibiting expansive properties were common throughout Australia. The damage to light structures founded on expansive soils in Victoria occurred mainly in properties built on quaternary basaltic clays and Tertiary to Ordovician clays. A review of existing literature in the area of expansive soils showed a lack of a thorough scientific diagnostic of the damage to light structures founded on expansive soils. Very few studies had been performed on damage to light structures on expansive soils in Victoria. There were no models so far to predict damage condition to light structures. More over, most of the reports on damage to light structures on expansive soils in Victoria were poorly documented. The aim of this research project was to develop a model to predict the damage condition of light structure on expansive soils in Victoria. A hybrid Neural Network trained with Genetic Algorithm was adopted for the de-velopment of the Predictive Damage Condition model. The Neural Network and Ge-netic Algorithm toolboxes from MATLAB� version 7.1 were used. The development of a Predictive Damage Condition model was driven by the shortage of defined quanti-tative studies and methods of selecting the factors that influenced the damage to light structure on expansive soils. The data used was based on information extracted from the Building Housing Commission which was recorded by different engineering companies based only on the tenants complain and site investigation of the properties. A series of factors that were believed to be dominant in influencing damage to light structures were chosen including: structural type, foundation, the presence of vegetation, soil type, age, and climate change. The model showed that it was able to resolve the problems facing light structures on expansive soils. First and foremost, the Predictive Damage Condition model was able to predict the damage condition or damage class using different combinations of fac-tors. It was also possible to identify the factors contributing to the damage of the struc-ture and to assess their relative importance in causing damage to light structures on expansive soil. It was found that the construction footing and vegetation were the most important among all the other input parameters. Change in Thornthwaite Moisture In-dex or climate was ranked second. Construction wall and age, were ranked third and fourth respectively while both region and geology were ranked fifth. In addition, Change in Thornthwaite Moisture Index was noted to have the strongest correlation with other input parameters.
37
Muttharam, M. "Engineering Behaviour Of Ash-Modified Soils Of Karnataka." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/256.
Full textAbstract:
During a survey of black cotton soil zones of Karnataka, indigenously stabilized black cotton soil deposits were encountered in Belgaum, Bijapur, Bagalkot and Gadag Districts of Karnataka. These modified black cotton soils have low swelling and negligible shrinkage tendencies. Owing to their low volume change potential on moisture content changes, these soils are widely preferred in earth construction activities. The exact origin of these modified black cotton soil deposits is not known. According to anecdotal references, these soils were prepared by mixing unknown proportions of wood ash, organic matter and black cotton soil and allowing them to age for unknown periods of time. As wood-ash was apparently used in their preparation, these modified black cotton soils are referred to as ash-modified soils (AMS) in the thesis.
The practice of preparing ash-modified soils is no longer pursued in black cotton soil regions of Karnataka and the available supply of this indigenously stabilized soil is being fast depleted. Also, attempts have not been made to characterize the physico-chemical and engineering properties of AMS deposits of Karnataka. Given the widespread utilization of ash-modified soils in black cotton soil areas of Karnataka, there is a need to understand their physico-chemical and engineering behaviour and the physico-chemical mechanisms responsible for their chemical modification.
Swelling and shrinkage of expansive soil deposits are cyclic in nature due to periodic climatic changes. Chemically stabilized black cotton soil deposits are also expected to experience cyclic wetting and drying due to seasonal climatic changes. The impact of cyclic wetting and drying on the swelling behaviour of natural expansive soils is well-documented. However, the impact of alternate wetting and drying on the swelling behaviour of admixture stabilized expansive soils (these include natural - ash-modified soils and laboratory - lime stabilized black cotton soils) has not been examined. Such a study would be helpful to assess the long term behaviour of admixture stabilized soils in field situations.
To achieve the above objectives, experiments are performed that study:
1.The physico-chemical and engineering properties of ash-modified soils from different Districts of Karnataka. The physico-chemical and engineering properties of natural black cotton soil (BCS) specimens from locations adjacent to ash-modified soil deposits are also examined to understand and evaluate the changes in the engineering characteristics of the ash-modified soils due to addition of admixtures.
2. Identify the physico-chemical mechanisms responsible for the chemical stabilizationof ash-modified soils.
3.The influence of cyclic wetting and drying on the wetting induced volume changebehaviour of admixture stabilized black cotton soils, namely, ash-modified blackcotton soils and lime stabilized black cotton soils.
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Muttharam, M. "Engineering Behaviour Of Ash-Modified Soils Of Karnataka." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/256.
Full textAbstract:
During a survey of black cotton soil zones of Karnataka, indigenously stabilized black cotton soil deposits were encountered in Belgaum, Bijapur, Bagalkot and Gadag Districts of Karnataka. These modified black cotton soils have low swelling and negligible shrinkage tendencies. Owing to their low volume change potential on moisture content changes, these soils are widely preferred in earth construction activities. The exact origin of these modified black cotton soil deposits is not known. According to anecdotal references, these soils were prepared by mixing unknown proportions of wood ash, organic matter and black cotton soil and allowing them to age for unknown periods of time. As wood-ash was apparently used in their preparation, these modified black cotton soils are referred to as ash-modified soils (AMS) in the thesis.
The practice of preparing ash-modified soils is no longer pursued in black cotton soil regions of Karnataka and the available supply of this indigenously stabilized soil is being fast depleted. Also, attempts have not been made to characterize the physico-chemical and engineering properties of AMS deposits of Karnataka. Given the widespread utilization of ash-modified soils in black cotton soil areas of Karnataka, there is a need to understand their physico-chemical and engineering behaviour and the physico-chemical mechanisms responsible for their chemical modification.
Swelling and shrinkage of expansive soil deposits are cyclic in nature due to periodic climatic changes. Chemically stabilized black cotton soil deposits are also expected to experience cyclic wetting and drying due to seasonal climatic changes. The impact of cyclic wetting and drying on the swelling behaviour of natural expansive soils is well-documented. However, the impact of alternate wetting and drying on the swelling behaviour of admixture stabilized expansive soils (these include natural - ash-modified soils and laboratory - lime stabilized black cotton soils) has not been examined. Such a study would be helpful to assess the long term behaviour of admixture stabilized soils in field situations.
To achieve the above objectives, experiments are performed that study:
1.The physico-chemical and engineering properties of ash-modified soils from different Districts of Karnataka. The physico-chemical and engineering properties of natural black cotton soil (BCS) specimens from locations adjacent to ash-modified soil deposits are also examined to understand and evaluate the changes in the engineering characteristics of the ash-modified soils due to addition of admixtures.
2. Identify the physico-chemical mechanisms responsible for the chemical stabilizationof ash-modified soils.
3.The influence of cyclic wetting and drying on the wetting induced volume changebehaviour of admixture stabilized black cotton soils, namely, ash-modified blackcotton soils and lime stabilized black cotton soils.
39
SOUZA, Leonardo Sebastiao de. "Análise do comportamento mecânico de um solo expansivo da província petrolífera de Urucu-AM para fins de pavimentação." Universidade Federal de Goiás, 2009. http://repositorio.bc.ufg.br/tede/handle/tde/1319.
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Previous issue date: 2009-10-30The establishment of transportation infrastructure is critical to the development of the Urucu- AM region, a newly developed oil exploration area in the Amazonas state. The construction of such infrastructure is challenging due to the lack of suitable materials for the construction pavement base and subbase courses and adverse weather conditions, with alternating heavy rainfall and drought periods. Besides the shortage of suitable granular material, the presence of expansive soils is often verified. The presence of expansive soils associated with inadequate moisture content during compaction, results in the occurrence of cracks in the pavements, drastically reducing its performance and lifetime. A quantitative understanding of this type of problem requires the analysis of the interaction between the unsaturated soil surface and the atmosphere and the study the mechanical behavior (stress-strain) of unsaturated soil. Such understanding requires the determination of the variations in soil moisture and total volume. The quantification of tensile stresses also requires the establishment or evaluation of the constitutive relations of the unsaturated expansive soils involved. Experiments were conducted in the laboratory with the objective of characterizing the hydraulic and mechanical behavior of expansive soils from Urucu-AM. Chemical, physical and mineralogy characterization tests were carried out for the soil. Geotechnical characterization and Proctor compaction tests and compression were performed. To study the soil in the unsaturated condition, the main focus of this work, tests were performed using the filter paper technique and the axis translation technique under oedometric conditions. For the suction controlled oedometric tests, a cell developed specially for this purpose was employed. The oedometer allows for the independent control of vertical stress and matric suction and the monitoring of the variation of moisture and total volume study. State surfaces for void ratio, degree of saturation and gravimetric moisture content were determined. The results obtained show the expected mechanical behavior of the soil under wetting paths.
O estabelecimento de uma infra-estrutura de transporte é fundamental para o desenvolvimento da região denominada de província petrolífera de Urucu-AM. A construção desta infraestrutura esbarra em varias dificuldades entre elas a escassez de materiais adequados para a construção de bases e sub-bases de pavimentos e as condições climáticas adversas, com alternância de períodos de alta pluviosidade e períodos de estiagem. Além da escassez de material granular adequado, observa-se com freqüência a presença de solos argilosos expansivos. A presença de tais solos, associada às condições freqüentemente inadequadas de umidade de compactação, resulta na ocorrência de trincas nos pavimentos, reduzindo drasticamente o seu desempenho e vida útil. Um entendimento quantitativo do problema requer a análise da interação entre o solo não saturado de superfície e a atmosfera e o estudo do comportamento mecânico (tensão-deformação) do solo não saturado. Tal entendimento passa pela determinação das variações de umidade do solo e sua variação volumétrica total. A quantificação das tensões de tração requer também o estabelecimento ou avaliação de relações constitutivas dos solos expansivos não saturados envolvidos. Foram conduzidos experimentos em laboratório com o objetivo de caracterizar o comportamento hidráulico e mecânico de solos expansivos de Urucu-AM. Inicialmente foram realizadas análises químicas, caracterização física e determinação da mineralogia, para caracterização das macro e microestruturas dos solos estudados. Foram executados também ensaios de caracterização geotécnica e compactação Proctor. Para o estudo do solo na condição não saturado, principal enfoque desta dissertação, foram realizados ensaios de papel filtro e de adensamento com controle de sucção. Para o ensaio de adensamento com controle de sucção foi utilizada uma prensa oedométrica especialmente desenvolvida para este fim. Como esta prensa foi possível aplicar de forma independente tensões verticais, sucção matricial e monitorar a variação de umidade e de volume do solo em estudo. As superfícies de estado de índice de vazios, grau de saturação de umidade do solo foram determinadas. Os resultados obtidos permitiram a determinação do comportamento do solo compactado durante trajetórias de molhagem.
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Osman, Norhaslinda Yasmin. "The development of a predictive damage condition model of light structures on expansive soils using hybrid artificial intelligence techniques." Australasian Digital Thesis Program, 2007. http://adt.lib.swin.edu.au/public/adt-VSWT20070731.124824/index.html.
Full textAbstract:
Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, 2007.Submitted in fulfilment of requirements for the degree of Doctor of Philosophy, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2007. Typescript. Includes bibliographical references (p. 174-202).
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Tu, Hongyu. "Prediction of the Variation of Swelling Pressure and 1-D Heave of Expansive Soils with respect to Suction." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32515.
Full textAbstract:
The one-dimensional (1-D) potential heave (or swell strain) of expansive soil is conventionally estimated using the swelling pressure and swelling index values which are determined from different types of oedometer test results. The swelling pressure of expansive soils is typically measured at saturated condition from oedometer tests. The experimental procedures of oedometer tests are cumbersome as well as time-consuming for use in conventional geotechnical engineering practice and are not capable for estimating heave under different stages of unsaturated conditions. To alleviate these limitations, semi-empirical models are proposed in this thesis to predict the variation of swelling pressure of both compacted and natural expansive soils with respect to soil suction using the soil-water characteristic curve (SWCC) as a tool. An empirical relationship is also suggested for estimating the swelling index from plasticity index values, alleviating the need for conducting oedometer tests. The predicted swelling pressure and estimated swelling index are then used to estimate the variation of 1-D heave with respect to suction for expansive soils by modifying Fredlund (1983) equation. The proposed approach is validated on six different compacted expansive soils from US, and on eight field sites from six countries; namely, Saudi Arabia, Australia, Canada, China, US, and the UK. The proposed simple techniques presented in this thesis are friendly for the practitioners for using when estimating the heave in unsaturated expansive soils.
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Venkata, Swamy B. "Stabilisation Of Black Cotton Soil By Lime Piles." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/219.
Full textAbstract:
Modification of black cotton soils by chemical admixtures is a common method for stabilizing the swell-shrink tendency of expansive soils. Advantages of chemical stabilization are that they reduce the swell-shrink tendency of the expansive soils and also render the soils less plastic. Among the chemical stabilization methods for expansive soils, lime stabilization is most widely adopted method for improving the swell-shrink characteristics of expansive soils.
Lime stabilization of clays in field is achieved by shallow mixing of lime and soil or by deep stabilization technique. Shallow stabilization involves scarifying the soil to the required depth and lime in powder or slurry form is spread and mixed with the soil using a rotovator. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays Deep stabilization using lime can be divided in three main groups: lime columns, lime piles and lime slurry injection. Lime columns refer to creation of deep vertical columns of lime stabilized material. Lime piles are usually holes in the ground filled with lime. Lime slurry pressure injection, as the name suggests, involves the introduction of a lime slurry into the ground under pressure.
Literature review brings out that lime stabilization of expansive clays in field is mainly performed by mixing of lime and soil up to shallow depths. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays. Use of lime in deep stabilization of expansive soils however has not been given due attention. There exists a definite need to examine methods for deep stabilization of expansive soils to prevent the deeper soil layers from causing distress to the structures in response to the seasonal climatic variations. In addition, there exists a need for in-situ soil stabilization using lime in case of distressed structures founded on expansive soil deposits.
The physical mixing of lime and soil in shallow stabilization method ensures efficient contact between lime and clay particles of the soil. It however has limitation in terms of application as it is only suited for stabilization of expansive soils to relatively shallow depths. Studies available have not compared the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soils.
To achieve the above objectives laboratory experiments are performed that study:
1. the efficacy of lime piles in stabilizing compacted black cotton soil specimens from
Chitradurga District in Karnataka. The efficiency of lime piles in chemically stabilizing
the compacted black cotton soil mass was investigated as a function of:
a)amount of lime contained in the lime pile
b)radial migration of lime from the central lime pile
c)migration of lime as a function of soil depth
2. the relative impact of the lime pile technique and lime-soil mixing method in altering the
physico-chemical, index and engineering properties of expansive black cotton soil.
The organization of this thesis is as follows
After the first introductory chapter, a detailed review of literature performed towards highlighting the need to examine stabilization of expansive soils using lime pile technique is brought out in Chapter 2.
Chapter 3 presents a detailed experimental programme of the study. 25 mm and 75 mm diameter lime piles were installed in the compacted soil mass to study the influence of amount of lime contained in the lime pile on the soil properties. The amount of quick lime contained in the 25 mm and 75 mm lime piles corresponded to 1 % and 3 % by dry weight of the soil mass respectively. Radial and vertical migration of lime from the central lime pile was examined by sampling soil specimens at different radial distances from the central lime pile and at different depths of soil sample. At a given depth and radial distance, migration of lime was estimated by comparing the exchangeable cation composition, pH and pore salinity of the treated soil with that of the natural (untreated) black cotton soil specimen. Alterations in the soil engineering properties at a given depth and radial distance were evaluated by comparing the index properties, swell potential and unconfined compressive strength of the lime pile treated soil specimen with those of the untreated specimen. To compare the relative efficiency of lime mixing and lime pile technique in altering the swelling behaviour of black cotton soil, batches of black cotton soil specimens were treated with 1 % and 3 % quick lime on dry soil weight basis. The compacted soil-lime mixes were cured at moisture contents of 31-34 % for a period of 10 days. The physico-chemical, index and engineering properties of the 1 % lime mixed specimens are compared with those of the 25 mm lime pile treated specimens. The properties of the 3 % lime mixed soil specimens are compared with those of the 75 mm lime pile treated specimens.
Chapter 4 examines the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. Experimental results showed that controlling the swell potential of deep expansive soil deposits is possible by the lime pile technique. Treatment with lime pile caused migration of dissociated calcium and hydroxyl ions into the surrounding soil mass. In case of 25 mm lime pile, the experimental setup allowed measurement of migration of lime up to three times the lime pile diameter. In case of 75 mm lime pile, the experimental setup allowed measurement of migration of lime up to 1.6 times pile diameter. In both experiments, migration of lime was also uniform through out the soil depth of 280 mm. Migration of calcium and hydroxyl ions increased the pore salinity and pH of the treated soil mass. The increase in pH caused clustering of additional exchangeable calcium ions at the negative clay particle edges. The increased pore salinity and exchangeable calcium ions reduced the diffuse ion layer thickness that in turn suppressed the plasticity index and the swell potential of the compacted expansive soil. The laboratory results hence bring out that lime pile treatment in the field can substantially reduce the swell potential of the soil at least to a radial extent of 2 to 3 times the lime pile diameter.
The 75 mm lime pile contained lime content in excess of the initial consumption of lime (ICL) value of the black cotton soil - namely 2.6 %. Laboratory results showed that migration of hydroxyl ions even from the 75 mm pile could not elevate the soil pH to levels required for soil-lime pozzoIonic reactions (pH ≥12). The very low solubility of lime in water (< 1 g/litre) and the impervious nature of the black cotton soil are considered to have impeded efficient interactions between lime and soil in course of treatment of the expansive soil with lime piles. Absence of soil-lime pozzolonic reactions precluded the formation of cementation compounds in the lime pile treated soil specimens. Cementation compounds formed by the soil-lime pozzolonic reactions are responsible for the much higher strengths of lime stabilized soils. Consequently, treatment with 25 mm pile had no impact on the unconfined compressive strength of the black cotton soil. Comparatively, treatment with 75 mm lime pile slightly increased the strength of the treated soil due to increased inter-particle attraction and particle flocculation.
Chapter 5 compares the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. Experimental results showed that mixing of soil and lime promote stronger chemical interactions between lime released hydroxyl ions and clay particles than that achieved by diffusion of lime from a central lime pile. The more alkaline pH of the lime mixed soil specimens rendered the clay particle edges more negative. Consequently, more calcium ions were adsorbed at the clay particle edges of the lime mixed soil specimens imparting them higher exchangeable calcium contents than the lime pile treated soil specimens. Also, at 3 % lime addition, the pH of the lime-mixed soil was sufficiently high (in excess of 12) to cause dissolution of silica and alumina from the clay lattice necessary for the formation of cementation compounds. The stronger lime modification reactions plus the lime-soil pozzolonic reactions (applicable for soil treated with lime content greater than ICL value) achieved by the lime mixing technique rendered the expansive soil much less plastic, much less expansive and much stronger than the lime pile treated specimens. The results of the laboratory study hence suggest that if a choice exists in the field between conventional method of spreading-mixing-compacting of soil-lime mixes and treating the ground with lime piles, the former technique should be adopted because of its greater efficacy in stabilizing the expansive soil.
Chapter 6 summarizes the findings of the study.
43
Venkata, Swamy B. "Stabilisation Of Black Cotton Soil By Lime Piles." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/219.
Full textAbstract:
Modification of black cotton soils by chemical admixtures is a common method for stabilizing the swell-shrink tendency of expansive soils. Advantages of chemical stabilization are that they reduce the swell-shrink tendency of the expansive soils and also render the soils less plastic. Among the chemical stabilization methods for expansive soils, lime stabilization is most widely adopted method for improving the swell-shrink characteristics of expansive soils.
Lime stabilization of clays in field is achieved by shallow mixing of lime and soil or by deep stabilization technique. Shallow stabilization involves scarifying the soil to the required depth and lime in powder or slurry form is spread and mixed with the soil using a rotovator. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays Deep stabilization using lime can be divided in three main groups: lime columns, lime piles and lime slurry injection. Lime columns refer to creation of deep vertical columns of lime stabilized material. Lime piles are usually holes in the ground filled with lime. Lime slurry pressure injection, as the name suggests, involves the introduction of a lime slurry into the ground under pressure.
Literature review brings out that lime stabilization of expansive clays in field is mainly performed by mixing of lime and soil up to shallow depths. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays. Use of lime in deep stabilization of expansive soils however has not been given due attention. There exists a definite need to examine methods for deep stabilization of expansive soils to prevent the deeper soil layers from causing distress to the structures in response to the seasonal climatic variations. In addition, there exists a need for in-situ soil stabilization using lime in case of distressed structures founded on expansive soil deposits.
The physical mixing of lime and soil in shallow stabilization method ensures efficient contact between lime and clay particles of the soil. It however has limitation in terms of application as it is only suited for stabilization of expansive soils to relatively shallow depths. Studies available have not compared the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soils.
To achieve the above objectives laboratory experiments are performed that study:
1. the efficacy of lime piles in stabilizing compacted black cotton soil specimens from
Chitradurga District in Karnataka. The efficiency of lime piles in chemically stabilizing
the compacted black cotton soil mass was investigated as a function of:
a)amount of lime contained in the lime pile
b)radial migration of lime from the central lime pile
c)migration of lime as a function of soil depth
2. the relative impact of the lime pile technique and lime-soil mixing method in altering the
physico-chemical, index and engineering properties of expansive black cotton soil.
The organization of this thesis is as follows
After the first introductory chapter, a detailed review of literature performed towards highlighting the need to examine stabilization of expansive soils using lime pile technique is brought out in Chapter 2.
Chapter 3 presents a detailed experimental programme of the study. 25 mm and 75 mm diameter lime piles were installed in the compacted soil mass to study the influence of amount of lime contained in the lime pile on the soil properties. The amount of quick lime contained in the 25 mm and 75 mm lime piles corresponded to 1 % and 3 % by dry weight of the soil mass respectively. Radial and vertical migration of lime from the central lime pile was examined by sampling soil specimens at different radial distances from the central lime pile and at different depths of soil sample. At a given depth and radial distance, migration of lime was estimated by comparing the exchangeable cation composition, pH and pore salinity of the treated soil with that of the natural (untreated) black cotton soil specimen. Alterations in the soil engineering properties at a given depth and radial distance were evaluated by comparing the index properties, swell potential and unconfined compressive strength of the lime pile treated soil specimen with those of the untreated specimen. To compare the relative efficiency of lime mixing and lime pile technique in altering the swelling behaviour of black cotton soil, batches of black cotton soil specimens were treated with 1 % and 3 % quick lime on dry soil weight basis. The compacted soil-lime mixes were cured at moisture contents of 31-34 % for a period of 10 days. The physico-chemical, index and engineering properties of the 1 % lime mixed specimens are compared with those of the 25 mm lime pile treated specimens. The properties of the 3 % lime mixed soil specimens are compared with those of the 75 mm lime pile treated specimens.
Chapter 4 examines the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. Experimental results showed that controlling the swell potential of deep expansive soil deposits is possible by the lime pile technique. Treatment with lime pile caused migration of dissociated calcium and hydroxyl ions into the surrounding soil mass. In case of 25 mm lime pile, the experimental setup allowed measurement of migration of lime up to three times the lime pile diameter. In case of 75 mm lime pile, the experimental setup allowed measurement of migration of lime up to 1.6 times pile diameter. In both experiments, migration of lime was also uniform through out the soil depth of 280 mm. Migration of calcium and hydroxyl ions increased the pore salinity and pH of the treated soil mass. The increase in pH caused clustering of additional exchangeable calcium ions at the negative clay particle edges. The increased pore salinity and exchangeable calcium ions reduced the diffuse ion layer thickness that in turn suppressed the plasticity index and the swell potential of the compacted expansive soil. The laboratory results hence bring out that lime pile treatment in the field can substantially reduce the swell potential of the soil at least to a radial extent of 2 to 3 times the lime pile diameter.
The 75 mm lime pile contained lime content in excess of the initial consumption of lime (ICL) value of the black cotton soil - namely 2.6 %. Laboratory results showed that migration of hydroxyl ions even from the 75 mm pile could not elevate the soil pH to levels required for soil-lime pozzoIonic reactions (pH ≥12). The very low solubility of lime in water (< 1 g/litre) and the impervious nature of the black cotton soil are considered to have impeded efficient interactions between lime and soil in course of treatment of the expansive soil with lime piles. Absence of soil-lime pozzolonic reactions precluded the formation of cementation compounds in the lime pile treated soil specimens. Cementation compounds formed by the soil-lime pozzolonic reactions are responsible for the much higher strengths of lime stabilized soils. Consequently, treatment with 25 mm pile had no impact on the unconfined compressive strength of the black cotton soil. Comparatively, treatment with 75 mm lime pile slightly increased the strength of the treated soil due to increased inter-particle attraction and particle flocculation.
Chapter 5 compares the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. Experimental results showed that mixing of soil and lime promote stronger chemical interactions between lime released hydroxyl ions and clay particles than that achieved by diffusion of lime from a central lime pile. The more alkaline pH of the lime mixed soil specimens rendered the clay particle edges more negative. Consequently, more calcium ions were adsorbed at the clay particle edges of the lime mixed soil specimens imparting them higher exchangeable calcium contents than the lime pile treated soil specimens. Also, at 3 % lime addition, the pH of the lime-mixed soil was sufficiently high (in excess of 12) to cause dissolution of silica and alumina from the clay lattice necessary for the formation of cementation compounds. The stronger lime modification reactions plus the lime-soil pozzolonic reactions (applicable for soil treated with lime content greater than ICL value) achieved by the lime mixing technique rendered the expansive soil much less plastic, much less expansive and much stronger than the lime pile treated specimens. The results of the laboratory study hence suggest that if a choice exists in the field between conventional method of spreading-mixing-compacting of soil-lime mixes and treating the ground with lime piles, the former technique should be adopted because of its greater efficacy in stabilizing the expansive soil.
Chapter 6 summarizes the findings of the study.
44
Torres, Rueda Juan Diego, and Paucar Angel Mitzuo Watanabe. "Efectos de la adición de cloruro de potasio en el comportamiento expansivo de suelos arcillosos en la ciudad de Talara." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/654498.
Full textAbstract:
La expansividad de suelos es un fenómeno ampliamente reconocido, al cual se le atribuye una copiosa cantidad de problemas estructurales suscitados a nivel mundial. Precisamente, la incidencia de su comportamiento en los antecedentes históricos registrados, propició una marcada tendencia científica por estudiar los factores desencadenantes, así como encontrar técnicas y/o materiales eficientes para su estabilización. En ese afán, la presente investigación pretende evaluar la contribución del cloruro de potasio en el comportamiento expansivo de suelos arcillosos de alta plasticidad. Para ello, se efectuaron ensayos de identificación mineralógica, caracterización física y determinación del grado de expansión, obteniendo como principal resultado una significativa reducción de los parámetros expansivos del suelo.Soil swelling is a widely known problem, which is related to a huge number of structural problems all over the world. In fact, due to its negative behavior in structures, which have been recorded many times in preceding documents, experts have focused their aim on studying the factors that made expansive soils extremely dangerous, as well to find techniques and/or materials that assure the efficiency of their stabilization. In that commitment, this investigation pretends to evaluate the effects of potassium chloride in the expansive behavior of high-plasticity clay soils. For this purpose, mineralogical identification, physical characterization and degree of expansion determination tests were made, the results of which mainly express a significant reduction of the swelling characteristics of this type of soils.
Trabajo de investigación
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Dardé, Benjamin. "Experimental and numerical study of the hydromechanical behaviour of bentonite pellet-powder mixtures." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC1030.
Full textAbstract:
Les matériaux à base de bentonite sont envisagés pour la réalisation des ouvrages de fermeture dans les concepts de stockage de déchets radioactifs. Dans ce contexte, les matériaux mis en place sous forme de mélanges de granules (pellets) de bentonite sont étudiés car ils présentent moins de contraintes d’installation comparés aux blocs préfabriqués. Les pellets sont disposés dans les galeries à l’état sec et forment un matériau granulaire. Le matériau est humidifié par l’eau issue de la roche encaissante et acquiert une texture homogène. Avant homogénéisation, le caractère granulaire du matériau contrôle son comportement.Ce travail se concentre sur la caractérisation expérimentale et la modélisation numérique d’un mélange de pellets et pellets concassés (poudre) de bentonite en proportion 70/30 en masse sèche, envisagé pour réaliser les ouvrages de fermeture dans le concept français de stockage de déchets radioactifs. La proposition, l’implémentation et la validation d’un modèle de comportement tenant compte de la nature granulaire initiale et d’éventuelles hétérogénéités locales de densité est l’objectif principal de ce travail.L’influence de la nature granulaire est mise en évidence par l’intermédiaire d’essais de pression de gonflement à succion contrôlée au laboratoire. Les essais sont réalisés sur des échantillons préparés à différentes teneurs en poudre. A partir d’une caractérisation expérimentale à l’échelle du pellet, un modèle simple décrivant le comportement hydromécanique du pellet est proposé et implémenté dans un code de calcul utilisant la méthode des Éléments Discrets (DEM). Les essais réalisés au laboratoire sur les échantillons sans poudre sont simulés par la DEM et le modèle proposé. Les résultats expérimentaux sont reproduits de manière satisfaisante. Cette méthode est utilisée pour simuler de larges assemblages granulaires de densités variées soumis à des sollicitations hydromécaniques. Les paramètres influençant le comportement macroscopique des assemblages de pellets à l’état « granulaire » sont identifiés à partir de ces simulations. Un ensemble de lois de comportement sont proposées pour modéliser le matériau comme un milieu continu.La transition de l'état granulaire à l’état homogène est décrite par des critères faisant intervenir la succion et les fractions volumiques relatives des pellets et de la poudre. Une version modifiée du Barcelona Basic Model est proposée pour modéliser le comportement du matériau à l’état « homogène ». Le modèle est implémenté dans le code de calcul par Éléments Finis (FEM) BIL. Les essais de pression de gonflement réalisés au laboratoire sur des échantillons contenant différentes teneurs en poudre sont reproduits de manière satisfaisante, sur l’ensemble du chemin d’humidification, en utilisant un unique jeu de paramètres.Le comportement du matériau au cours de l’humidification en conditions de volume constant est finalement étudié à plus grande échelle par la réalisation d’essais d’imbibition en modèle réduit au laboratoire, à différentes teneurs en poudre. Les cellules sont de section carrée avec une face vitrée. Une caméra permet l’observation de l’évolution de la texture du matériau au cours de l’humidification. La prédominance des transferts en phase vapeur dans le processus de saturation du matériau, l’influence et l’évolution de la structure granulaire au cours de l’humidification et l’influence de la teneur en poudre sur la réponse macroscopique du mélange sont mis en évidence. Des lois de transferts hydriques sont proposées à partir des résultats et observations expérimentales et implémentées dans le code BIL. La perspective principale de ce travail est la réalisation de simulations à plus grande échelle en utilisant le modèle développé. Ainsi, des problématiques inhérentes à l’utilisation des mélanges de pellets et poudre, notamment la nature granulaire initiale et les hétérogénéités locales de densité, pourront être prises en compteBentonite based materials are considered as a sealing material in radioactive waste disposal concepts because of their low permeability, radionuclide retention capacity and ability to swell upon hydration, thus filling technological gaps. Within this context, bentonite pellet mixtures have been studied owing to operational convenience. Pellets are laid in the galleries in a dry state as a granular assembly. The mixture progressively becomes more homogeneous upon hydration by the pore water of the host rock. Before homogenisation, the granular structure of the material controls the macroscopic behaviour of the mixture.The present work focuses on the experimental characterisation and numerical modelling of a mixture of bentonite pellet and crushed pellet (powder), in proportion 70/30 in dry mass, a candidate sealing material in the French concept of radioactive waste disposal. The proposition, implementation and validation of a new modelling framework, considering features such as the initial granular structure of the material or local heterogeneities of densities, is the main objective of this PhD work.The influence of the initial granular structure is evidenced by performing suction-controlled swelling pressure tests in the laboratory, using samples of various powder contents. From grain-level experimental characterisation, a simple model describing the hydromechanical behaviour of a pellet is proposed and implemented in a Discrete Element Method (DEM) code. Using DEM and the proposed model, aforementioned swelling pressure tests performed on samples containing no powder are satisfactorily simulated. The same method is used to model large granular assemblies of various pellet densities upon hydromechanical loadings. Relevant parameters involved in the macroscopic behaviour of pellet mixtures in “granular” state are identified from simulation results and constitutive laws are proposed to describe the hydromechanical behaviour of these materials using a continuum mechanics approach.The transition from “granular” state to “homogenised” state is described by criteria proposed from experimental results and data available in the literature and involves suction and relative volume fractions of pellet and powder. A modified version of the Barcelona Basic Model is proposed to model the material behaviour in “homogenised” state. The proposed model is implemented in the Finite Element Method (FEM) code BIL. Using a single set of parameters, all swelling pressure tests performed in the laboratory are satisfactorily reproduced in FEM simulations along the entire hydration path.The material behaviour upon hydration in constant volume condition is finally studied at a larger scale by performing mock-up imbibition tests, using various powder contents. Cells have a square section; a glass side and a camera allow the texture to be observed during hydration. The dominance of vapour transfers in the saturation process of the material, the influence and evolution of the granular structure upon hydration, and the influence of the powder content on the macroscopic response are notably identified. Transfer laws are proposed to describe the observed material behaviour in the mock-up tests and implemented in BIL.The realisation of larger scale coupled simulations using the proposed hydromechanical model is a perspective arising from this PhD work. Predictive simulations could be performed at the structure scale, considering relevant features such as the initial granular structure and local heterogeneities of density in the sealing plugs
46
Li, Kai. "Modélisation du comportement hydromécanique des sols gonflants basée sur la théorie de l'état limite." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAD004/document.
Full textAbstract:
Les matériaux argileux sont soumis aux chemins complexes de succion/contrainte qui se manifestent par des désordres affectant principalement les structures construites en surface et les ouvrages enterrés. Dans ce contexte, il est important d’appréhender le comportement hydromécanique de ces matériaux afin de mieux maîtriser leur utilisation. Le comportement hydromécanique complexe des matériaux argileux est directement relié à leur structure interne qui a été le principal sujet de plusieurs études sur la micro- et macrostructure des sols. Ces études ont conduit aux développements des modèles élastoplastiques pour sols gonflants. Les modèles existants sont capables de simuler le comportement principal de sol gonflant non saturé, mais ils présentent un grand nombre de paramètres, ce qui prend du temps pour le calcul. Par conséquence, on propose une méthode simplifiée pour modéliser le comportement hydromécanique des sols gonflants basée sur la théorie de l’état limite. Ce modèle est tout d’abord validé par les résultats de l’essai oedométrique. Ensuite, il est implanté dans un code aux éléments finis (CAST3M) pour simuler le comportement in situ des sols gonflants. Enfin, l’application de la théorie de l’état limite au sol gonflant avec une grande densité est effectuée par la combinaison de l’écrouissage cinématique et l’écrouissage isotropeClayey materials are often subjected to the complex suction/stress paths, causing many problems in both surface structures and buried structures built on them. In this context, it is important to study the hydromechanical behavior of these materials in order to better control their use in civil engineering. The complex hydromechanical behavior of clay materials is basically connected to their fabric which has been the main subject of several studies on the micro- and macrostructure of soils. These studies have led to the development of elastoplastic models for expansive soils. The existed models are able to simulate the basic behavior of unsaturated expansive soil, but present a large number of model parameters, leading to a time-consuming calculation. Therefore, we propose a simplified method to model the hydromechanical behavior of expansive soils based on shakedown concept. This model is first validated by the experimental results of cyclic suction-controlled oedometer tests. Then, it is implemented in a finite element code (CAST3M) to simulate the in-situ behavior of expansive soils. Finally, the application of shakedown theory to heavily dense expansive soils is carried out by considering a combined hardening plasticity
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Assadollahi, Tejaragh Hossein. "L’impact des événements climatiques et de la sécheresse sur le phénomène du retrait gonflement des argiles en interaction avec les constructions." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD011/document.
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Le changement climatique et les événements climatiques sévères tels que les périodes de sécheresse/humidification prolongées sont à l'origine du phénomène de retrait-gonflement dans les sols argileux. Ce phénomène est affecté par les interactions sol-végétation-atmosphère (SVA) et peut causer d’importants dommages structurels aux constructions légères telles que les bâtiments résidentiels. L’objectif de ce travail de recherche est de modéliser le comportement in situ du retrait-gonflement des sols gonflants dans un contexte SVA en se basent sur des outils numériques. Une méthode d'interaction sol-atmosphère est initialement présentée accompagnée d’un modèle couplé hydro-thermique du sol. Cette approche a été principalement mise en place afin de déterminer les conditions aux limites temporelles à la surface du sol en se basent sur la notion du bilan de masse et d'énergie pour déterminer a posteriori, les modifications spatio-temporelles de la succion du sol, de la teneur en eau et de la température. Cette approche a été validée à l'aide des observations in situ des sites instrumentés. Par la suite, l’influence de l’absorption d’eau par les végétations a été intégrée dans le terme source de l’écoulement de l’eau dans un milieu non saturé, à l’aide d’un modèle d’absorption d’eau de racine existant.Les variations temporelles de succion ont été postérieurement reliées au comportement volumique du sol en appliquant une approche simple développée à partir des résultats expérimentaux des essais de séchage/humidification réalisés dans la littérature. Les indices associés dans le plan indice des vides-log succion, ainsi que les paramètres complémentaires du modèle linéaire ont été corrélés aux paramètres géotechniques de base. L'approche proposée a été ultérieurement validée avec des données in situ fournies par la surveillance d’un site expérimental. Le site expérimental de Roaillan a été instrumenté afin de surveiller les modifications physiques du sol ainsi que le comportement structurel du bâtiment. Les comparaisons entre les résultats de la modélisation et les observations in situ de la succion du sol, la teneur en eau, la température et les mouvements du sol dans le temps ont montré une performance acceptable du modèle. L’approche a ensuite été appliquée pour étudier l’influence des projections climatiques futures (2050) sur les variables physiques et les mouvements du sol sur ce site. Trois scénarios RCP relatifs aux changements climatiques ont été examinés dans cette étude, qui ont révélé des différents comportements possibles à court terme et à long terme. Finalement, l'approche développée a été appliquée au territoire français en le divisant en six régions climatiques. Différents paramètres de sol ont été attribués à chacune de ces régions climatiques afin de définir les conditions de référence. En conséquence, l’influence de différents facteurs externes sur les mouvements du sol a été analysée sur une période donnée. Enfin, l’étude suggère les mesures adéquates à prendre pour minimiser l’amplitude du phénomène de retrait et de gonflement dans un contexte SVAClimate change and severe climatic events such as long drought/rehydration periods are at the origin of the shrinkage and swelling phenomenon in expansive soils. This phenomenon is affected by Soil-Vegetation-Atmosphere (SVA) interactions and can cause severe structural damage to lightly loaded constructions such as residential buildings. The objective of this re-search work is to simulate the in-situ behavior of the shrinkage-swelling in expansive soils in a SVA context using numerical tools. A soil-atmosphere interaction method is primarily presented along with a coupled hydro-thermal soil model. This approach was established in order to determine primarily, the natural time variable boundary conditions at the considered soil surface based on the mass and energy balance concept, and secondly to determine the spatial-temporal changes of the soil suction, water content and temperature. This approach was validated using in situ observations of monitored sites. Thereafter, the influence of the water uptake by vegetation was incorporated in the source term of the unsaturated water flow theory, using an existing root water uptake model. Subsequently, the temporal variations of the soil suction were related to the volume change behavior using a simple approach developed based on the experimental results of drying/wetting tests performed in the literature. The associated volumetric indices in the void ratio-log suction plan, along with the complementary parameters of the linear model were correlated with basic geotechnical parameters. The proposed approach was validated with in situ data provided from an experimental site. The Roaillan experimental site was instrumented in order to monitor the soil’s physical changes along with the structural behavior of the building. Comparisons between the simulated and observed soil suction, soil water content, temperature and soil movements in time and depth showed an acceptable performance of the predictions. The approach was then extended to study the influence of future climate projections (2050) on the soil’s physical variables and movements. Three RCP climate change scenarios were considered in this analysis which revealed different possible behavior in both short term and long term. Finally, the developed approach was applied to the French territory by dividing it to six different climatic regions. Different soil parameters were attributed to each of these climatic regions in order to set the reference condition. Thereafter, the influence of different external factors was analyzed on the soil movements over a chosen period. The study finally suggests the adequate actions to take for minimizing the amplitude of the shrinkage and swelling phenome-non in a SVA context
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Pusari, Quispe Oscar Alonso, and Machuca Joao Yhazzir Rodriguez. "Estudio experimental de mejoramiento de las propiedades de resistencia al corte de un suelo expansivo con polvo de vidrio reciclado y fibras de polipropileno en la ciudad de Talara, departamento de Piura." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/653985.
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Los resultados del estudio que se expone en la presente tesis, tratan sobre las arcillas expansivas en “Talara”, en base a resultados obtenidos en los ensayos de laboratorio como el Análisis Granulométrico por Tamizado, ensayo de Límite Líquido, Límite Plástico e Índice de Plasticidad, ensayo de Proctor modificado y el ensayo Corte Directo. Cabe decir que dichos ensayos se realizaron tomando como punto de partida las características geológicas, geomorfológicas, geotécnicas y la evaluación de daños en las diversas estructuras de la zona como viviendas producto de la expansión y consolidación del terreno. La problemática se origina a raíz del suelo arcilloso, ya que la principal característica que puede tener ese tipo de suelo es que sea un suelo expansivo, por lo tanto, se debe tener en consideración mejorar el suelo para evitar posteriormente daños estructurales. En la investigación se describirán las principales consecuencias y factores que intervienen en el fenómeno de la expansión y el cómo enfrentar a este tipo de suelo. El presente estudio busca la mejora del suelo mediante una técnica innovadora, eco amigable y factible como es la estabilización física usando el vidrio reciclado y las fibras de polipropileno (materiales de desecho en las operaciones de la construcción), ya que en la actualidad estos dos tipos de materiales generan un impacto negativo en el medio ambiente, por lo cual se trata de reutilizar dichos materiales en el mejoramiento del suelo. El estudio se basó en una muestra de suelo medianamente expansivo, debido al registro del Límite Líquido, Límite Plástico e Índice de Plasticidad, extraído de la Urbanización Sudamérica, localizado en Talara, Piura con el fin de mejorarlo, para luego verificar el comportamiento de mejora de las propiedades de resistencia al corte del suelo. Como parte del desarrollo de la investigación se realizaron los diversos ensayos para comprobar con datos numéricos la mejora del suelo, otorgando porcentajes de sustitución con respecto al peso seco (0%, 5%, 6% y 7.5%) a la muestra en estado natural. Finalmente, se obtuvieron las mejoras de las propiedades de resistencia al corte con un porcentaje de sustitución equivalente a 5%, el cual registra las mejoras en cohesión y ángulo de fricción.The results of the study that is presented in this thesis, deals with the expansive clays in "Talara", based on results obtained in laboratory tests such as the Granulometric Analysis by Screening, Liquid Limit test, Plastic Limit and Plasticity Index, modified Proctor test and the Direct Cut test. It is possible to say that these tests were carried out taking as a starting point the geological, geomorphological, geotechnical characteristics and the evaluation of damages in the different structures of the area as houses product of the expansion and consolidation of the land. The problem originates from the clay soil, since the main characteristic that this type of soil can have is that it is an expansive soil, therefore, it is necessary to consider improving the soil to subsequently avoid structural damage. The research will describe the main consequences and factors involved in the phenomenon of expansion and how to deal with this type of soil. The present study seeks to improve the soil through an innovative, eco-friendly and feasible technique such as physical stabilization using recycled glass and polypropylene fibers (waste materials in construction operations), since these two are currently Types of materials generate a negative impact on the environment, so it is about reusing these materials in soil improvement. The study was based on a sample of moderately expansive soil, due to the registry of the Liquid Limit, Plastic Limit and Plasticity Index, extracted from the South American Urbanization, located in Talara, Piura in order to improve it, and then verify the improvement behavior of the properties of resistance to the cut of the floor. As part of the development of the research, the various tests were carried out to verify the improvement of the soil with numerical data, granting replacement percentages with respect to dry weight (0%, 5%, 6% and 7.5%) to the sample in its natural state . Finally, the improvements of the properties of resistance to the cut with a percentage of substitution equivalent to 5% were obtained, which records the improvements in cohesion and angle of friction.
Tesis
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Russell, Adrian Robert Civil & Environmental Engineering Faculty of Engineering UNSW. "Cavity expansion in unsaturated soils." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2004. http://handle.unsw.edu.au/1959.4/22263.
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The problem of cavity expansion in unsaturated soils is investigated. A unified constitutive model for unsaturated soils is presented in a critical state framework using the concepts of effective stress and bounding surface plasticity theory. Consideration is given to the effects of suction and particle crushing in the definition of the critical state. A simple isotropic elastic rule is adopted. A loading surface and bounding surface of the same shape are defined using simple and versatile functions. A limiting isotropic compression line exists, towards which the stress trajectories of all isotropic compression load paths approach. A non-associated flow rule is assumed for all soil types. Isotropic hardening/softening occurs due to changes in plastic volumetric strains as well as suction for some unsaturated soils, enabling account of the phenomenon of volumetric collapse upon wetting. Results of isotropic compression tests, oedometric compression tests and drained and undrained triaxial compression tests performed on Kurnell (quartz) sand in saturated and unsaturated states and subjected to stresses sufficient to cause particle crushing are presented and used to calibrate the model. The model is also calibrated using results reported in the literature for triaxial tests performed on saturated and unsaturated speswhite kaolin and three load paths. For both soils the model leads to a much improved fit between simulation and experiment compared to that for models based on conventional plasticity theory. The model is implemented into a cavity expansion analysis using the similarity technique, extended for application to unsaturated soils. Cylindrical and spherical cavities are considered, as are drained and undrained conditions. Cavity expansion results for the bounding surface model and conventional plasticity models are compared for saturated conditions. Substantial differences highlight the importance of adopting a model that accurately describes stress-strain behaviour. Cavity expansion results for the bounding surface model and saturated and unsaturated conditions are also compared. Substantial differences, particularly in the limit pressure, highlight the major influence of suction and the importance of accounting for this when using cavity expansion theory to interpret results of the cone penetration and pressuremeter tests.
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Abed, Ayman A. "Numerical modeling of expansive soil behavior /." Stuttgart : IGS, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016534652&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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