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1
Lacoul, Sriranjan. "Consolidated-drained shear-strength of unsaturated soil." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66044.
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Barzegar, Abdolrahman. "Structural stability and mechanical strength of salt-affected soils." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phb296.pdf.
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Copies of author's previously published articles in pocket inside back cover. Bibliography: leaves 147-160. This thesis outlines the factors affecting soil strength and structural stability and their interrelationship in salt-affected soils. The objectives of this study are to investigate the influence of clay particles on soil densification and mellowing, the mellowing of compacted soils and soil aggregates as influenced by solution composition, the disaggregation of soils subjected to different sodicities and salinities and its relationship to soil strength and dispersible clay and the effect of organic matter and clay type on aggregation of salt-affected soils.
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Rouaiguia, Ammar. "Strength of soil-structure interfaces." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/26883.
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This research work deals with the development of the shearbox apparatus by introducing a micro-computer to automatically collect all the results, and to apply normal and shear stresses. A continuous statement of time, channel number, and transducer input and output is produced for each test, the sequences of applied rates of displacement and normal stresses for which were programmed.
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Chung, Sun-Ok. "On-the-go soil strength profile sensor /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3137684.
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Cho, Gye Chun. "Unsaturated soil stiffness and post-liquefaction shear strength." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/21010.
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Wende, Jon T. "Predicting soil strength with remote sensing data." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/5174.
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Approved for public release; distribution is unlimitedPredicting soil strength from hyperspecral imagery enables amphibious planners to determine trafficability in the littorals. Trafficability maps can then be generated and used during the intelligence preparation of the battlespace allowing amphibious planners to select a suitable landing zone. In February and March 2010, the Naval Research Laboratory sponsored a multi-sensor remote sensing and field calibration and field validation campaign (CNMI'10). The team traveled to the islands of Pagan, Tinian, and Guam located in the Marianas archipelago. Airborne hyperspectral imagery along with ground truth data was collected from shallow water lagoons, beachfronts, vegetation, and anomalies such as World War II relics. In this thesis, beachfront hyperspectral data obtained on site was used as a reference library for evaluation against airborne hyperspectral data and ground truth data in order to determine soil strength for creating trafficability maps. Evaluation of the airborne hyperspectral images was accomplished by comparing the reference library spectra to the airborne images. The spectral angle between the reference library and airborne images was calculated producing the trafficability maps amphibious planners can use during the intelligence preparation of the battlespace.
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Young, Iain McEwing. "Soil strength and hard-setting behaviour of some structurally unstable British soils." Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU010498.
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A study was made of the physical properties of a number of structurally sensitive soils some of which exhibited behaviour characteristic of hard-setting soils (soils which when wet slump and set hard, on drying presenting problems in terms of ease of cultivations and root growth). Work concentrated on an examination of soils of the Wick series at two sites at the Institute of Horticultural Research, Wellesbourne, where there is a documented history of consistent differences in crop yields between sites. The worse site (Big Ground) had been intensively managed for considerably longer than the better one (Plum Orchard). Dry bulk density measurements over the growing season suggest that slumping occurred on both sites. Big Ground had the greatest bulk density (typically over 1.65 g/cm3). Field and laboratory penetrometer measurements have shown that under relatively dry (an 8% moisture content) conditions roots would experience severe mechanical impedence on both sites. Root counts at final harvest showed that conditions for rooting were considerably worse in Big Ground where all roots were confined to the top 30 cm. Root growth was better in Plum Orchard and was concentrated in between peds, which did not exist at Big Ground. Laboratory strength (unconfined compressive and indirect tensile) and friability measurements on equilibrated samples also showed up differences between the two sites; the greates differences existing between 1 and 10 bar tension with Big Ground samples exhibiting the greatest strengths and least friabilities. On both sites strengths were observed to increase sharply for a comparatively small decrease in moisture content. Implications of these results are discussed with reference to ease of cultivation and rootability. Another light texured soil from Elgin, known for its tendency to erode, was chosen as a contrast to the Wellesbourne sites. Soil at this site was shown to have much less of a tendency to slump and to create problems for root growth, compared to the Wellesbourne sites. The Elgin soil was also considerably weaker, and the sharp increase in strength observed at Wellesbourne was not observed in Elgin. A new test for water suspendable solids, performed on the Wellesbourne and Elgin soils as well as on 5 other soils known for their structural instability showed that, with the exception of the Elgin soil, a large amount of silt sized material could be brought into suspension with little soild disturbance. An explanation for hard-setting behaviour which is based on those results is suggested.
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Elbanna, E. B. E. "Agricultural machinery selection : Soil strength and operational timeliness." Thesis, University of Edinburgh, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371883.
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Sinclair, John. "Crusting, soil strength and seedling emergence in Botswana." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU363198.
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This thesis gives the results of an investigation of the strengths and particularly the crust forming potential of arable soils from Botswana and the relationship to seedling emergence of sorghum, the most important crop in Botswana and one that because of its small seed weight (about 2 0 mg) can fail to emerge through a hard soil crust. A review of the literature suggested that the soil factors which had to be considered were dispersibility of clay and factors which affect this, and the bulk density of the soils. Soils which are found in many tropical and sub-tropical regions, with low organic matter and inactive clays can set hard after a simple wetting and drying cycle. In these soils, the strength is very strongly dependent on the water content, showing a hyperbolic or exponential relationship-, and the strengths when dry may be very greatly increased by remoulding the wet soil. The crust strength required to prevent seedling emergence varies with the size of the seedling and for cotton (seed weight about 80 mg), 1-3 MPa penetration resistance measured with a penetrometer is sufficient to prevent emergence. Seedlings exert a total force proportional to their number. In the experimental programme, seedlings' forces were measured, seedling emergence observed in a field experiment under crusting conditions, and the strength characteristics of a group of soils, representative of arable soils in Botswana, studied. A sorghum seedling was found to exert a maximum force of about 1 N or dividing by the area of the plumule, a pressure of about 0,5 MPa. The field experiment showed that much better emergence was obtained from planting 15 seeds together than from planting 4 seeds together when a crust formed after planting. A study of 32 soils, most of them sand to sandy loam in texture but with a few clays and hydroirorphic soils, from arable areas in Botswana showed the sandy to sandy loam soils to have high bulk densities ( 1,45-1 ,75 Mg/m3) and extremely low organic carbon contents (0,12-0,85 g/100g). The bulk densities of all the soils were inversely related to the organic carbon content and this was itself related to the clay content of the soils. The bulk densities of the sands were dependent on the grading of the sand fraction. Many of the soils were sensitive to remoulding in the Emerson test and the sands to loany sands had 0,4-1,0 g/100 g water dispersible clay. Measurements of tensile strength on air-dry samples showed that all the soils, except for one sand, set hard after a wetting and drying cycle, giving for vacuum wet samples indirect tensile strengths 1,0-14,4 kPa. For the sands to sandy loams this strength was related to the water dispersible clay content. Samples wet at atmospheric pressure were weaker than the vacuum wet samples, the reduction in strength was related to the air porosity of the non-vacuum wet soils prior to drying. Remoulding the soils prior to drying them increased the strength by a factor of up to 50 times, giving strengths from 4 kPa to 600 kPa. The strength after remoulding was dependent on the Emerson index. Compacting the soils increased their strength greatly and to an extent that agreed with the hypothesis that the strength obtained was proportional to the area of contact between the particles. Experiments on penetration resistance at a range of water contents were performed on a few soils. A hyperbolic relationship between water content and penetration resistance of the surface soil was found for sand to sandy loam soils, with the maximum resistance of dry soils above 2 MPa. The penetration resistance of the sandy loam soil was Increased three times by disturbing it when wet. Sprinkler wetting the sieved soils was not found to affect the penetration resistance by a large amount compared and other methods of welting. Penetration resistance was measured on air-dry samples of most of the main group of soils following varying degrees of wetting with a rainfall simulator. The clays and hydromorphic soils gave very low values of penetration resistance under these conditions, showing that at organic carbon contents of about 1% and clay contents from 20 to 30%, the decreased bulk density and tendency to form aggregates' on drying overcame the tendency to set hard. The mean values for the sands to sandy loams were from 1 to 6 MPa so all these soils could offer significant resistance to a sorghum seedling. The penetration resistance of the sands and loam/ sands depended on their bulk densities and water dispersible clay contents, while the penetration resistance of the sandy loams depended only on the water dispersible clay content.
10
Keller, Thomas. "Soil compaction and soil tillage - studies in agricultural soil mechanics /." Uppsala : Dept. of Soil Sciences, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a489.pdf.
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Stark, Timothy D. "Mechanisms of strength loss in stiff clays." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/74771.
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On September 14, 1981 a major slide was discovered in the upstream slope of San Luis Darn, located about 100 miles southeast of San Francisco, California. The slide occurred at the end of a period of rapid drawdown of the reservoir. Although this was the longest and fastest drawdown in the life of the dam, 180 feet in 120 days, there had been seven previous cycles of drawdown, some nearly as severe as the one that preceded the slide.
Field measurements showed the slide was caused by the clayey slopewash material left in the foundation of the dam during construction. Although the slopewash was dry and extremely strong when the embankment was built, it apparently was weakened considerably when submerged beneath the reservoir and its strength was further degraded by cyclic loading effects as the reservoir level was raised and lowered during the 14 years preceding the slide.
The objective of this research was to gain a better understanding of the mechanisms of strength loss in the slopewash that resulted in the 1981 slide at San Luis Dam. This was accomplished using laboratory tests on undisturbed samples of slopewash, analyses of seepage through the embankment and foundation, finite element analyses of stresses in the dam during construction and operation of the reservoir, and conventional equilibrium slope stability analyses.
The laboratory tests showed that the shear strength of the slopewash decreases very quickly when the desiccated material is wetted. Wetting causes immediate reduction in shear strength to the fully softened value, and there is no lasting effect of consolidation by drying. After wetting the highly desiccated slopewash has the same strength as in the remolded, normally consolidated condition.
Tests that simulated cyclic changes in normal stress and shear stress like those during drawdown and refilling of the reservoir showed that further strength loss results from cyclic loading of the slopewash. Cyclic loading at stress levels below the fully softened peak strength result in continual shear displacement, and eventually, when the cumulative horizontal displacement reaches approximately ten inches, the shear strength is reduced to its residual value.Ph. D.
12
Mui, Tak Sang. "The shearing effect of suction /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20MUI.
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Limprasert, Tawan. "Behaviour of soil, soil-cement and soil-cement-fiber under multiaxial test." Ohio University / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1179260769.
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Yin, Penghai. "Tensile Strength of Unsaturated Soils." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41841.
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Desiccation-induced soil cracking is of significant interest in several engineering disciplines, which include geotechnical and geoenvironmental engineering, mining engineering, and agriculture engineering. The hydraulic, mechanical, thermal and other physico-chemical properties of unsaturated soils can be predominantly influenced due to cracks. Reliable information of these properties is required for the rational design and maintenance of earth structures taking account of the influence the soil-atmosphere interactions (e.g., for expansive soil slopes, earth dams, and embankments). In spite of significant research studies published in the literature on the desiccation-induced cracks during the past century, the fundamental mechanism of crack initiation and propagation of soils induced by drying and shrinkage is still elusive. For this reason, the focus of this thesis is directed towards understanding the tensile strength of unsaturated soils which is associated with soil crack initiation criterion (i.e. maximum tensile stress criterion).
Tensile strength is the key property of soils for interpreting the initiation of soil cracking from a macroscopic point of view. A semi-empirical model is proposed for predicting the tensile strength of unsaturated cohesionless soils taking into account the effect of both the negative pore-water pressure in saturated pores and the air-water interfacial surface tension in unsaturated pores. The proposed model is calibrated and validated by providing comparisons between the model predictions and the experimental measurements on 10 cohesionless soils (i.e. five sandy soils and five silty soils) published in the literature. The proposed model is simple and requires only the information of Soil-Water Characteristic Curve (SWCC) and Grain Size Distribution curve (GSD), which can be obtained from conventional laboratory tests.
To investigate the influence of microstructure, a practical and reliable estimation approach for predicting the evolution of the microstructural void ratio of compacted clayey soils subjected to wetting and drying paths is proposed. The microstructural evolution of 13 examined soils were investigated quantitatively using the mercury intrusion porosimetry (MIP) results. The investigated soils include four high-plasticity clays, eight low-plasticity clays and a glacial till which is a relatively coarse-grained soil with some fines. Based on this study, a novel criterion has been developed for identifying different pore populations of compacted clayey soils. The “as-compacted state line” (ACSL) was proposed to estimate the initial microstructural void ratio based on the compaction water ratio. A constitutive stress is derived to interpret and predict the volumetric deformation of compacted clay aggregates. The linear elastic constitutive model is used for predicting the microstructural void ratio of the examined compacted soils following monotonic wetting and drying paths. The developed approach (i.e. the ACSL and the linear elastic constitutive model) is validated by providing comparisons between the predicted and interpreted microstructural void ratios for all the examined soils.
In addition to the matric suction and microstructure, the confining pressure also influences the tensile strength of unsaturated compacted clayey soils. The tensile strength tests on a compacted clayey soil by both the direct method (i.e. triaxial tensile test) and the indirect method (i.e. Brazilian split test) were performed. It is found that the tensile strength increases as the compaction water content decreases for the range investigated in this study, which could be explained by the variation of the inter-aggregated capillary bonding force and the change in microstructure. The increase in the confining pressure has been found to induce the change in failure mode (i.e. from pure tensile failure mode to combined tensile-shear failure mode). In spite of limitations associated with the Brazilian split test, tensile strength is widely determined using this test due to the simple procedure of specimen preparation and wide availability of test equipment in conventional laboratories. However, the Brazilian tensile strength is found to overestimate the tensile strength of compacted specimens with water content greater than the plastic limit. This is due to the considerable plastic deformation associated with the ductile failure instead of brittle failure.
In summary, this thesis is devoted to providing insight into the fundamental mechanisms associated with the desiccation-induced crack initiation by quantitatively investigating the various factors that influence the tensile strength of unsaturated soils, which include the matric suction, the microstructure, and the confining pressure from theoretical studies and laboratory investigations.
15
Yung, See Yuen. "Determination of shear wave velocity and anisotropic shear modulus of an unsaturated soil /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20YUNG.
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Orman, Marc Elliot 1958. "A study of bedding intrustion into low strength subgrade." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/558102.
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Al-Ghanem, Abdulhakim M. F. "Factors affecting the strength characteristics of calcium-carbonate - cemented soils." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184645.
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The factors which affect the engineering properties of calcium carbonate cemented soil are examined. The influence of calcium carbonate content, molding moisture content, and confining pressure on the strength characteristics of two types of soil is investigated in two distinct phases of the research. Type A soil, obtained from the University of Arizona Campbell Avenue Farm in Tucson, was used for the artificially cemented specimen stage. It is composed of sand and silt-size particles with some clay and is virtually free of calcium carbonate in its natural state. Sierrita soil, obtained from the Twin Buttes Open Pit Mine south of Tucson, was used for the reconstituted sample stage. It is naturally cemented with calcium carbonate and is composed mainly of sand, gravel, a small amount of silt, and occasional large-sized (boulder and cobble) particles. Specimens for triaxial compression testing were compacted for each phase of the study under carefully controlled conditions. Three test series were carried out on Type A soil artificially cemented with calcium carbonate. Three percentages (0%, 15%, and 30%) on a dry weight basis of the soil were used. Two molding water contents, one dry and one wet of optimum moisture content, were established for each test series. Unconsolidated undrained triaxial compression tests were carried out on oven-dried specimens at three different confining pressures to obtain shear strength parameters. The fabric characteristics of selected specimens were then defined by viewing them under a scanning electron microscope. The results indicate that the strength of the calcium carbonate cemented soil depends on the distribution and not necessarily the content of the cementing agent within the soil mass. Visual examination of the various microstructures of the artificially cemented soil confirmed the hypothesis that strength gain occurs when the calcium carbonate particles are concentrated at the points of contact between soil grains. Visual examination of the fabric of the naturally cemented Sierrita soil showed the microstructure to be highly compressed with weathered calcium carbonate particles dominating the soil structure. The calcium carbonate content was found to range from 14 to 23%. Because of sampling difficulties, an in situ cohesion value for the Sierrita soil could not be obtained from conventional laboratory tests. Therefore, the value was obtained by back analysis of the stability of actual slopes existing at Twin Buttes Mine. Slope stability analyses using Bishop's Modified Method with a search routine based on the Simplex Method of Nelder and Mead were performed. Stability analyses were also performed using strength properties of artificially cemented Type A soil. These analyses showed the relationships among cohesion, friction angle, safety factor, and calcium carbonate content for a specified slope geometry.
18
Grant, Cameron Douglas. "Soil structure and tensile strength in relation to the microtopography of soil fracture surfaces." Adelaide, 1989. http://hdl.handle.net/2440/18940.
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Grant, Cameron Douglas. "Soil structure and tensile strength in relation to the microtopography of soil fracture surfaces." Thesis, Adelaide, 1989. http://hdl.handle.net/2440/18940.
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Misra, Rabindra Kumar. "Root growth and phosphorus uptake in relation to soil structure and strength /." Title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phm6781.pdf.
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Lemos, Luis Joaquim Leal. "The effect of rate on residual strength of soil." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/7643.
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Hoque, Md Nurul. "Estimation soil strength from a two-point indentation test." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315806.
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SILVA, TIAGO PROTO DA. "PULL-OUT STRENGTH OF NAILS IN GNAISSIC RESIDUAL SOIL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7926@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORA presente pesquisa trata da avaliação da resistência ao arrancamento de grampos em solo residual de gnaisse. Foram realizados ensaios de arrancamento em uma obra de solo grampeado executada em um maciço de solo residual de gnaisse. A resistência ao arrancamento foi avaliada em 4 cotas diferentes ao longo do perfil de escavação. Foram realizados 8 ensaios de arrancamento em grampos de 4m de comprimento. Quatro ensaios foram executados em grampos instrumentados com strain-gages, para avaliar a distribuição das cargas de tração durante os estágios de carregamento. Foram também realizados ensaios de cisalhamento direto no solo e na interface solo/cimento para avaliação das propriedades mecânicas destes materiais. Amostras indeformadas foram coletadas imediatamente à frente dos furos de instalação dos grampos ensaiados garantindo uma maior representatividade dos materiais. Uma relação semi-empírica é proposta para se avaliar a resistência do solo e da interface solo/nata de cimento, obtidos em ensaios de cisalhamento direto no laboratório. Os resultados obtidos nesta pesquisa são comparados com ensaios realizados por outros autores, em encostas de solos residuais de gnaisse e empregados para validação da relação desenvolvida.
The present research presents an evaluation of the pullout resistance of nails in residual gneissic soil. Pullout tests were carried out in 4 different levels of the nailed wall with nails 4m long. Four tests were carried out in strain-gauged nails for evaluating the tension distribuition along the nail. A series of direct shear tests in soil specimens and in the soil/grout interface were also performed for obtaining the mechanical properties of these materials. Undisturbed samples had been collected very close to the pull-out test locations. A semi-empirical relation is proposed for evaluating the pullout resistance of nails, based on the shear strenghth parameters of the soil and of the soil/grout interface from laboratory direct shear tests.
24
Alzahrani, Saeed Kloofah. "Effect of Time on Soil-Geomembrane Interface Shear Strength." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1493060387473436.
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Xu, Jia. "Investigation of spatially graded distribution of pore fluid effect on wetting-induced soil collapse /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202008%20XU.
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Park, Jin Young. "A critical assessment of moist tamping and its effect on the initial and evolving structure of dilatant triaxial specimens." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/23949.
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Wang, Chwen-Huan. "Prediction of the residual strength of liquefied soils /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/10138.
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Win, San San Civil & Environmental Engineering Faculty of Engineering UNSW. "Tensile strength of compacted soils subject to wetting and drying." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2006. http://handle.unsw.edu.au/1959.4/31157.
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Knowledge of the stress-strain relationship of the compacted soils in tension is of importance for understanding of cracking that occurs in earth structures, in particular embankment dams and landfill barriers. Understanding the correlation between tensile properties and traditional soil parameters and soil suction is essential in identifying problems associated with desiccation induced cracking. A series of extensive laboratory experiments were performed on three different soils from existing embankment dams. This thesis concentrated on the investigation of tensile strength in relation to the type of soil, compaction water content, compaction density ratio, rate of loading, soil suction, moisture retention characteristics and the effect of drying and wetting. Stress-strain behaviour and tensile properties indicated a dependence on soil type and compaction criteria. The plasticity index, clay content and type of mineral has shown a significant influence on tensile strength. Compaction dry of optimum resulted in an increase in strength. Compaction wet of optimum showed a decrease in strength and small increase in strain at failure. Higher compaction effort resulted in higher tensile strength, tensile stiffness and brittle stress-strain behaviour. Difference in loading rate revealed response time for initial tensile deformation as well as sustainable duration up to failure point. The effect of soil suction plays an important role in drying during which specimens exhibited a considerable strength increase. The magnitude of strength increase may have been contributed by a combination of suction, air entry value and compaction density. The effect of wetting could cause decreasing in suction and thus a reduction in strength. Based on the findings, it was concluded that the desiccation-induced may not necessarily occur due to an associated increase in tensile strength. However, an increase in tensile strength is likely to be accompanied by an increase in shrinkage. Therefore, desiccation-induced cracking is related to the interaction between moisture loss, change in soil suction, tensile stress and shrinkage.
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Holko, Jeffrey M. "Shear Strength Correlations for Ohio Highway Embankment Soils." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1205248711.
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Erb, Ronald T. "The effect of roots on the shearing strength of soil." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1119364987.
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Junaideen, Sainulabdeen Mohamed. "Failure of saturated sandy soils due to increase in pore water pressure." Thesis, Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B30708540.
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Ohu, John Olutunde. "Peatmoss influence on strength, hydraulic characteristics and crop production of compacted soils." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=71960.
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The quantitative effects of increasing the organic matter contents of three soils upon their susceptibility to compaction, the recovery of tilth after compaction and the fertility of the soils were investigated. These effects were further studied on the production of bush bean (Phaseolus vulgaris).Soil consistency limits, soil water status, applied pressure and organic matter contents were used to predict shear strength, penetration resistance and water retention characteristics of compacted soils, with the aim of meeting the widespread demand for possible techniques of soil compaction prediction.
Soil compaction increased the ability of the soils to retain moisture, increased penetration resistance, shear strength and decreased the available water capacity of soils. On the other hand, organic matter increased the ability of the soils to retain moisture, expanded the available water capacity and decreased the penetration resistance and shear strength of compacted soils.
Although soil compaction increased the stem diameter of bush bean; the height, yields and root dry matter of the crop decreased with higher compaction levels. On the contrary, higher organic matter levels increased the plant and yield parameters of the crop.
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Hellings, Jan Eise. "The strength and stiffness of soils associated with excavations." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47471.
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Tika, Theodora Michael. "The effect of rate of shear on the residual strength of soil." Online version, 1989. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.286384.
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Quinteros, Vicente Santiago. "Observations on the mobilization of strength in reinforced soil structures." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50919.
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Confidence in the design of reinforced retaining structures is based on a limited body of experimental field data from performance monitoring of a relatively small number of case studies. In order to improve upon that confidence in design, this research addresses the back-analysis of the only field study involving a reinforced steep slope with independent measurements of tensile force and strain, which was first described by Fannin & Hermann (1990). Knowing the mobilized strength in the reinforcement, a back-analysis was performed using widely accepted design practice, with the purpose of establishing the mobilized angle of friction within the backfill soil of the structure. The mobilized friction angle was compared with the findings of laboratory shear strength tests in direct shear, triaxial and plane-strain conditions. The comparison provides further evidence in support of the expectation that plane-strain conditions prevail within the reinforced steep slope, and the recommendation in the British code of practice to use the peak friction angle for design. Additionally, visual inspection and index testing on exhumed geogrid samples from the structure described by Fannin & Hermann (1990) established that the geogrid has experienced no major physical damage, nor any significant degradation associated with durability of the polymer material. Moreover, rapid loading creep tests data show excellent agreement between exhumed and typical values, implying no significant durability degradation in the geogrid of the Skedsmo structure. Accordingly, isochronous load-strain-time data can be used with confidence for predicting the long-term strain of geogrid reinforced soil structures.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Kyambadde, Benjamin Senyonga. "Soil Strength and Consistency Limits from Quasi-Static Cone Tests." Thesis, University of Brighton, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523435.
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Elder, Donald McGillivray. "Stress strain and strength behaviour of very soft soil sediment." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:48050e2f-832d-47f4-9e3b-b922176f451b.
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Introduction: When fine grained natural sediments or artificially produced waste materials are transported and deposited through water, several different phases of behaviour are observed. These have been described variously as suspension, free settling, compression settling, intermediate and consolidating soil phases. Transitions between each are not always distinct in terms of material properties or behaviour and time spent in the early phases before a conventional soil state is attained can be a significant proportion of the total period of engineering interest. The eventual state attained following procession through these stages may be very different to that if the soil had been remoulded at the same final density. Standard engineering models exist which can describe soil behaviour well in separate phases under particular conditions, but these are of limited validity when extended to more general conditions and wider volumetric ranges than those for which they were formulated. The number of factors required to describe the entire range of behaviour is consequently larger than that for any one phase, and many of these factors are more familiar in fields of chemistry, geology or sedimentology than in classical soil mechanics. This thesis discusses, in engineering terms, the engineering behaviour observed in a particular soil during the general sedimentation and self weight consolidation process. In the second chapter existing knowledge about behaviour at zero or low stresses is reviewed and evaluated with respect to common assumptions made, often implicitly, in formulating predictive models. It is shown that while these models have been extensively developed to a stage where they can approximate many aspects of soil behaviour, the lack of fundamental investigations carried out in parallel with their development has often led to inadequate appreciation of the causes of discrepancies between modelled and real behaviour. This has occurred particularly where standard geotechnical testing equipment and methods devised for stiff soils have been used to obtain global average relationships between engineering parameters. Even where modified tests have been developed, instrumentation has sometimes been inadequate and measurements too infrequent, so that data available have necessarily been analysed only in terms of constitutive forms assumed already. In chapter three experimental techniques are proposed which, where possible will allow soil behaviour to be examined under the least restrictive conditions of one dimensional compression so that basic engineering concepts may be analysed. Chapter four describes the testing programme and presents direct results of experiments. Chapter five analyses compression behaviour and establishes some trends which can be observed for particular parameters and relationships, and which exist between experiments under different initial and boundary conditions. Similar analysis of strength behaviour is undertaken in chapter six, where results obtained using different testing methods are compared. In the final chapter the general relevance of these results and their implications for engineering problems are discussed. Some suggestions are made for future work. Areas of application Improved knowledge about cohesive waterborne sediments can result in considerable savings for related industries. In the United Kingdom the annual cost of maintenance dredging is £25m (I.C.E. Costal Engineering Research Panel, 1985). In East Coast ports alone reduction of the distances travelled by each dredger would lead to a saving of £270,000 per annum, per kilometre reduction. Studies at Rotterdam Europort (Kirby, Parker, van Oostrum, 1979) show that although a channel dredged recently may quickly refill with sediment to a depth which echo-sounding techniques might indicate to be unnavigable, the strength may be so low as to allow passage of vessels virtually unimpeded. A density of 1.2 Mg/m3 is now used by the Rijkswaterstaat to define the "Nautical Depth" of a channel, stated to be "a density within the suspension above whose altitude vessels can safely sail." Dredging control using information from gamma ray densimeters has enabled production increases of up to 50% to be obtained in the Europort area. In the United States $30m was spent in a 5 year period on a dredging research programme aimed at improving disposal methods (Haliburton, 1977). Considerable volumes of waste material are also produced by the mining industry. The phosphate industry in Florida produces 40 million tons by dry mass per annum at an initial 3% solids by mass which even after two years retains void ratios around 10, due to the high content of attapulgite, a clay mineral consisting of long fibrous particles with large specific surface. Disposal areas for these clays occupy over 50,000 acres and are surrounded by 300 miles of dams, posing significant environmental and safety problems (Bromwell, Oxford, 1977). Failures of underwater slopes have been well documented. In muds deposited recently in the Mississippi Delta area very low shear strengths combine with apparently high excess pore pressures and presence of gas bubbles to cause instability for slope angles less than 1°. Recent research carried out a Oxford suggests that presence of gas may cause high excess pressures to be deduced where none exist. Duncan and Buchignani (1973) analysed a slope failure in San Francisco Bay which occurred during cutting of a slope from a normally consolidated clayey silt. The importance of accurate determination of an in situ parameters for analysis was shown by the estimated saving of $200,000 through using a slope of 7:8 rather than 1:1, decreasing the supposed safety factor from 1.26 to 1.17. Analysis of error sources showed that an error of only 4% in the soil density could reduce this safety factor by 10%. Similar problems due to changes in loading or boundary conditions occur where natural changes, such as increase in water current, cause erosion of a sediment layer which might, for example, be supporting an underwater cable or pipeline. In all these areas in situ property determination in solid of low density provides major problems. Density is often the only quantity that can be measured both accurately and continuously and then only when a stable platform can be maintained. Recovery of high quality samples from these layers is virtually impossible, so that there is a strong need for correlations between density and other properties such as strength and compressibility.
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Kelly, Darren. "Effect of particle loss on soil volume, strength and stiffness." Thesis, Edinburgh Napier University, 2015. http://researchrepository.napier.ac.uk/Output/8865.
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Soil particle loss can occur through biodegradation, erosion and dissolution. Yet there is little understanding of the mechanical changes that accompany these phenomena, especially where the size of particle removed is concerned. This study investigated the influence of particle loss on the volumetric, strength and small strain stiffness of analogue soils. These consisted of uniform Leighton Buzzard sand with selected salt particle sizes. Particle sizes chosen for experimental tests are representative of the fines that might be lost through an erosion process called suffusion in embankment dams or the various sizes that might be degraded and/or decomposed in landfill and mining wastes. A triaxial apparatus was modified to allow the in-situ dissolution of samples under triaxial stress states. This was achieved through the circulation of water through the pore-water pressure line with ow controlled by differential pressure using a peristaltic pump. Bender elements were installed to monitor changes in shear wave velocity before, during and after dissolution. Test results showed increases in void ratio in all dissolution tests. The influence of salt size and the stress under which tests were performed was found to have a limited impact on the magnitude of void ratio increase. Salt particle size did, however, affect the initial packing density of the sand-salt mixtures with fine salt sizes resulting in lower void ratios. Therefore, these tests showed lower post-dissolution void ratios. Coarse salt sizes initially densely prepared resulted in high post-dissolution void ratios close to the maximum void ratio for the Leighton Buzzard sand. Ultimately, post-dissolution void ratios determined the large-strain shearing behaviour. Therefore the fine salt tests, in which the post-dissolution void ratios were lowest, were the only tests to show minor peak strengths prior to the critical state with a shear behaviour described as strain-softening dilative. The comparatively high void ratios obtained in coarse salt tests showed no peak strength but a strain-hardening contractive behaviour. The structural role of salt particles within sand mixtures was continually assessed with evidence suggesting that salt particles maintainedtheir structural integrity under the stresses applied through loading and subsequent shearing in this study. The influence of particle loss on the critical state was also probed. Post-dissolution samples consistently showed higher critical void ratios than sand-only samples not subjected to particle loss. Most of the findings might be explained in the context of strong force chains and their stability which is in turn influenced by the amount and size of soluble particles. Shear wave velocities were shown to decrease significantly with dissolution of 15% of weight of salt irrespective of size. Associated small-strain stiffness moduli were found to decrease even more substantially. The reported changes illustrate the significant influence that particle removal has on the mechanical properties of soil and are discussed and analysedwithin this thesis.
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Ho, Man Lee. "Theoretical approach to quantify influence of inherent anisotropy on undrained steady state strength of sand /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20HO.
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Kim, Hyunki. "Spatial variability in soils stiffness and strength /." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-07132005-194445/.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.Mayne, Paul, Committee Member ; Frost, David, Committee Member ; Santamarina, Carlos, Committee Chair ; Rix, Glenn, Committee Member ; Ruppel, Carolyn, Committee Member.
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Bennett, Michael Dever. "Effect of Concentration of Sphagnum Peat Moss on Strength of Binder-Treated Soil." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/93210.
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Organic soils are formed as deceased plant and animal wildlife is deposited and decomposed in wet environs. These soils have loose structures, low undrained strengths, and high natural water contents, and require improvement before they can be used as foundation materials. Previous researchers have found that the deep mixing method effectively improves organic soils. This study presents a quantitative and reliable method for predicting the strength of one organic soil treated with deep mixing.
For this thesis, organic soils were manufactured from commercially available components. Soil-binder mixture specimens with different values of organic matter content, OM, binder content, water-to-binder ratio, and curing time were tested for unconfined compressive strength (UCS). Least-squares regression was used to fit a predictive equation, modified from the findings of previous researchers, to this data. The equation estimates the UCS of a deep-mixed organic soil specimen using its total water-to-binder ratio and mixture dry unit weight. Soil OM is incorporated into the equation as a threshold binder content, aT, required to improve a soil with a given OM; the aT term is used to calculate an effective total water-to-binder ratio.
This thesis reached several important conclusions. The modified equation was successfully fitted to the data, meaning that the UCS of some organic soil-binder mixtures may be predicted in the same manner as that of inorganic soil-binder mixtures. The fitting coefficients from the predictive equations indicated that for the soils and binder tested, specimens of organic soil-binder mixtures have a greater relative gain of UCS immediately after mixing compared to specimens of inorganic soil-binder mixtures. However, the inorganic mixtures generally have a greater relative gain of UCS during the curing period. The influence of curing temperature was found to be similar for organic and inorganic mixtures. For the organic soils and binder tested in this research, aT may be expressed as a linear or power function of OM. For both functions, the value of aT was negligible at values of OM below 45%, which reflects the chemistry of the organic matter in the peat moss. For projects involving deep mixing of organic soils, the predictive equation will be used most effectively by fitting it to the results of bench-scale testing and then checking it against the results of field-scale testing.Master of Science
Organic soils are formed continuously as matter from deceased organisms – mainly plants – is deposited in wet environs and decomposes. Organic soils are most commonly found in swamps, marshes, and coastal areas. These soils make poor foundation materials due to their low strengths. Deep mixing, or soil mixing, involves introducing a binder like Portland cement or lime into soil and blending the soil and binder together to form columns or blocks. Upon mixing, cementitious reactions occur, and the soil-binder mixture gains strength as it cures. Deep mixing may be performed using either a dry binder, known as dry mixing, or a binder-water slurry, referred to as wet mixing. Deep mixing may be used to treat either inorganic or organic soils to depths of 30 meters or greater. Contractor experience has shown that deep mixing is one of the most effective methods of improving the strength of organic soils. Lab-scale studies (by previous researchers) of wet mixing of inorganic soils have found that the strength of soil-binder mixtures can be expressed as a function of mixture curing time and curing temperature, as well as the quantity of binder used, or binder factor, and the consistency of the binder slurry. No corresponding expression has been generated for wet mixing of organic soils, although many studies on the subject have been performed by previous researchers. The goal of this research was to generate such an expression for one organic soil. The soil used was made of sphagnum peat moss, an organic material commonly found in nature, and an inorganic clay used by previous researchers in studies of deep mixing in inorganic soils. The binder used in this research was a Portland cement. For this research, 43 unique soil-binder mixtures were manufactured. Each mixture involved a unique combination of soil organic matter content, binder factor, and binder slurry consistency. After a soil-binder mixture was made, it was divided, placed into cylindrical molds, and allowed to cure. The temperature of the curing environment of the mixture was monitored. Mixture compressive strength was assessed after 7, 14, and 28 days of curing using two cylindrically molded specimens of the mixture. Data on mixture strength was then evaluated to assess whether it could be expressed as a function of the variables tested. iv This research determined that the strength of at least some organic soils improved with wet mixing can be expressed as a function of soil organic matter content, binder factor, binder slurry consistency, and mixture curing time and curing temperature. The function will likely prove useful to deep mixing contractors, who routinely perform lab-scale deep mixing trials on samples of the soils to be improved in the field. Assuming wet mixing is used, the results of the trials are used to select values of binder factor and binder slurry consistency for the project. The function generated from this research will allow deep mixing contractors to select these values more reliably during the lab-scale phase of their work.
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Asoudeh, Atefeh. "Identifying Residual Soil Parameters for Numerical Analysis of Soil Nailed Walls." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/367048.
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This thesis provides a detailed study of slope reinforcement in soil slopes using soil nails, anchors and other mechanical stabilization methods. The major emphasis is on the use of soil nails in slopes formed with mostly residual soils.
A comparative study has been performed reviewing the different methods of slope stability analysis, and the shear strength parameters used in stability analyses, the soil models used in numerical analyses, residual soil profiles and their detailed engineering properties used in previous studies and various computer software which are currently in use.
An important conclusion concerning previous studies on slope stabilisation is that although some of them have focused on residual soils and specifically on soil nailed walls based in residual soil, there is not enough evidence available to show the effect of different parameters including soil strength, soil stiffness and also modelling assumptions on the result of stability analysis.
Therefore, following a detailed discussion of the employed procedure for selection of geotechnical properties of residual soil, selection of modelling parameters for nailed wall, soil model and geotechnical software that were used, numerical models were built to perform a parametric study for stability assessment of nailed walls in residual soils.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Grifffith School of Engineering
Science, Environment, Engineering and Technology
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Anyi, Janan Toma. "Residual strength of clay at low normal stresses." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/28319.
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Reid, Richard A. "Triaxial permeability device." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/20036.
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Chan, Man Yiu. "The influence of wetting on the dynamic properties of completely decomposed granite in Hong Kong /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202002%20CHANM.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 131-136). Also available in electronic version. Access restricted to campus users.
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Schmidt, Kevin Michael. "Root strength, colluvial soil depth, and colluvial transport on landslide-prone hillslopes /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/6732.
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Phillips, Erin Katherine. "Investigation of Required Tensile Strength Predicted by Current Reinforced Soil Design Methodologies." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49246.
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Geosynthetic Reinforced Soil (GRS) is a promising technology that can be implemented
in walls, culverts, rock fall barriers, and bridge abutments. Its use in walls and abutments
is similar to Mechanically Stabilized Earth Walls (MSEW) reinforced with geosynthetics.
Both GRS and MSEW are reinforced soil technologies that use reinforcement to provide
tensile capacity within soil masses. However, the soil theories behind each method and
the design methodologies associated with GRS and MSEW technologies are quite
different.
Therefore, a study was undertaken to compare the required tensile strength predicted by
these various reinforced soil design methodologies. For the purposes of this study, the
required ultimate tensile strength was defined as the ultimate tensile strength needed in
the reinforcement after all applicable factors of safety, load factors, and reduction factors
were applied. The investigation explored both MSEW and GRS. GRS has been made an
FHWA "Every Day Counts" initiative. Due to the push to implement GRS technology, it
is critical to understand how GRS design methods differs from classic MSEW design
methods, specifically in the prediction of ultimate tensile strength required.
A parametric study was performed comparing five different reinforced soil analysis
methods. Two are current MSEW design methods and one was a proposed revision to an
existing MSEW design method. The final two were GRS design methods. These design
methods are among the most current and/or widely used design references in the United
States regarding reinforced soil technology. There are significant differences between the
methods in the governing soil theory particularly between GRS and MSEW design
methods. The goal of the study was to understand which design parameters had the most
influence on calculated values of the required ultimate tensile strength and nominal
"unfactored" tensile strength. A base case was established and a reasonable set of
parameter variations was determined. Two loading conditions were imposed, a roadway
loading scenario and a bridge loading scenario.
Based on parametric study findings, conclusions were drawn about which design
parameters had the most influence for different design methods. Additionally, the
difference in overall predicted required tensile strength was assessed between the various
methods. Finally, the underlying soil theory and assumptions employed by the different
methods and their influence on predicted required tensile strength values was interpreted.Master of Science
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Kulkarni, Renu Uday. "A potential technique to determine the unsaturated soil shear strength parameter." Texas A&M University, 2008. http://hdl.handle.net/1969.1/86016.
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The shear strength behavior of unsaturated soils is a complex phenomenon. The major factors that lead to the complex behavior are grain size, natural alteration in status of moisture and associated capillary potential. The need for research is felt to understand the various aspects associated with development of shear strength of unsaturated soils. The research is conducted to obtain the most economical and reliable design solutions. The magnitude of positive pore water pressure developed in saturated soil reduces the shear strength to a great extent. The tensile pore water pressure in the capillary meniscus developed around the soil grain contacts, on the contrary, enhances the factor of safety in the case of unsaturated soil mass. In this research, the shear strength of unsaturated soil is studied for a range of saturation based on the parametric study. The principle of effective stress has proven to be the basis for understanding the shear strength of saturated soil mass and it has provided an explanation for the geotechnical engineering problems.
The thesis presents a study on the shear strength of the soil specimen using the direct shear apparatus. The previous research was mainly directed towards evaluation of shear strength under controlled soil suction, by modifying the apparatus. A simple technique is put forward in this research by making use of the conventional direct shear apparatus for testing the unsaturated soil. The suction stress was induced in the soil specimen and the shear strength was evaluated. The soil water characteristic curve has been used in the research to determine the tensile pore water pressure. Hypothesis based on parametric study has been put forward to present a technique to determine the unsaturated soil shear strength parameter in the thesis.
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Yi, Sŏk-wŏn. "Influence of surface topography on interface strength and counterface soil structure." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19559.
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Shrestha, Rakshya. "Deep soil mixing and predictive neural network models for strength prediction." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607735.
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