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1
Paulse, Arnelia N. (Arnelia Natalie). "Soil stabilization by microbial activity". Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53593.
Testo completoAbstract (sommario):
Thesis (MSc)--Stellenbosch University, 2003.ENGLISH ABSTRACT: Microorganisms play an important role in the stability and maintenance of the ecosystem and in the condition of the soil. However, in their natural environment, microorganisms often experience changing and hostile conditions. They therefore need to be able to adapt physiologically and modify their micro-environment. Biofilm formation is one mechanism to establish favorable micro-environments. The extracellular polymeric substances (EPS) that are typically associated with biofilm formation may also have an impact on soil structure. The aim of this project was to evaluate the potential of microbial manipulation on EPS production and the possible impact thereof on soil structure in order to improve water retention. Specific objectives of this study included the screening of natural environments for EPS-producers, developing techniques to observe EPS production and accumulation in the pores between soil particles, measuring the effect of EPS production on soil water hydraulic gradient, as well as determining the fate and impact of EPS-producers when introduced to naturally-occurring soil microbial communities. Several environmental samples have been screened for EPS-producing microorganisms. Soil columns were then inoculated with these EPS-producers and the passage of 20 mlaliquots water through the columns measured at 3 or 4-day intervals. Microbes isolated from soil, through their EPS production capability proved to retain water more effectively than was the case for water-borne EPS-forming microbes. This phenomenon was further studied using flow cells, filled with soil and inoculated with the EPS-producers isolated from either soil or water. Fluorescence microscopy showed that the soil microbes produced EPS that clogged pores between sand particles more effectively. This clogging resulted in lowering the soil water hydraulic gradient. To evaluate the effect of EPS-producers on existing soil microbial communities, cell counts, Biolog™whole-community carbon utilization studies and T-RFLP (terminal-restriction fragment length polymorphism) analyses were performed. Shifts in the soil microbial community could not be readily seen by observing microbial numbers and T-RFLP-analysis, but was noticeable in carbon utilization patterns.
AFRIKAANSE OPSOMMING: Mikroorganismes speel 'n belangrike rol in die stabiliteit en instandhouding van die ekosisteem en in die kondisie van die grond. In hul natuurlike omgewing ervaar mikroorganismes dikwels veranderlike en ongunstige toestande. Mikroorganismes het dus nodig om hulself fisiologies aan te pas en verander hul mikro-omgewing daarvolgens. Biofilm-vorming is een meganisme om gunstige mikro-omgewings te skep. Die ekstrasellulêre polimeriese produkte (EPP) wat tydens biofilm-vorming gevorm word, mag ook 'n impak hê op die grondstruktuur. Die doel van hierdie projek was om die potensiaal van mikrobiese manipulasie op EPP-vorming te evalueer asook die moontlike impak daarvan op grondstruktuur wat sodoende waterretensie kon bevorder. Die spesifieke doelwitte van hierdie studie het ingesluit die isolasie van EPPproduseerders vanuit natuurlike omgewings, die ontwikkeling van verskeie tegnieke waarvolgens EPP-produksie en die akkumulasie daarvan in die porieë tussen gronddeeltjies bestudeer kon word, die effek van EPP-produksie op hidrouliese gradiënt van grondwater en om die lot en impak wat EPP-produseerders op natuurlike grondmikrobiese populasies te bepaal. Verskeie grond- en watermonsters was getoets vir die voorkoms van EPP-produserende mikroorganismes. Grondkolomme is geïnokuleer met EPP-produseerders en die vloei van 20 ml-volumes water deur die kolomme is gemeet met 3 of 4-dag intervalle. Grond-geïsoleerde mikrobes het beter waterretensie tot gevolg gehad as water- geïsoleerde mikrobes. Hierdie verskynsel was verder bestudeer deur die gebruik van vloeiselle, gevul met grond of sand en geïnokuleer met EPP-produseerders geïsoleer vanuit grond of water. Fluoressensie mikroskopie het aangetoon dat grondmikrobes EPP produseer wat die porieë tussen gronddeeltjies meer effektief verstop. Dié verstopping het gelei tot die verlaging van die grondwater se hidrouliese gradiënt wat bepaal is deur die gebruik van die konstante-vlak bepalingsmetode. Om die effek van EPP-produseerders op bestaande mikrobiese populasies te bepaal, is seltellings, Biolog™ heel-gemeenskap koolstofverbruik studies en T-RFLP (terminale-restriksie fragment-lengte polimorfisme) analises uitgevoer. Veranderinge in die mikrobiese populasie kon nie geredelik bloot deur die bepaling van mikrobiese getalle en T-RFLP-analise waargeneem word nie, maar wel met die koolstofverbruikspatrone.
2
Rafalko, Susan Dennise. "Rapid Soil Stabilization of Soft Clay Soils for Contingency Airfields". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/35985.
Testo completoAbstract (sommario):
Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have consistently been found to be among the most effective stabilizers for road and airfield applications, although recent developments show promise using nontraditional stabilizers. The purpose of this research is to determine the most effective stabilizers and dosage rates of stabilizers to increase the strength of soft clay soils (initial CBR = 2) within 72 hours for contingency airfields to support C-17 and C-130 aircraft traffic. Pavement design charts for various aircraft loading conditions were generated using the Pavement-Transportation Computer Assisted Structural Engineering Program, which was developed by the Engineering Research and Development Center to determine ranges of required strength and thickness for an underlying subbase layer and a top base layer, such as stabilized soil, crushed-aggregate, or aluminum matting. From laboratory studies, the required design strengths for many loading conditions were achieved by treating clay with 2%-4% pelletized quicklime for the underlying subbase layer, and treating clay with 2%-4% pelletized quicklime, 1% RSC15 fibers, and 11% Type III cement for the top base layer. While the base layer requires a minimum thickness of six inches, the required subbase layer thickness is often quite large and may be difficult to construct. However, newly developed construction equipment currently used for subgrade stabilization on civilian projects should be able to stabilize the soil down to these large required depths and make construction possible.Master of Science
3
Luginbuhl, Katharine. "Soil stabilization properties of flexible intruders". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74450.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 18).
In many locations, soil is held in place by the roots of plants. When these plants are removed or die, the soil loses its cohesive strength and erodes away. We seek to create artificial soil stabilizers that use the same physical principles as the plant roots. To investigate how flexible materials can stabilize soil, we use photoelastic particles to analyze the forces within a system when a flexible intruder is introduced to the system. We report on the increase in system forces as an effect of the flexible intruder and compare it to experiments with plant roots. Since soil is a granular material, using this method to increase the forces within patches of soil may help prevent erosion or landslides.
by Katharine Luginbuhl.
S.B.
4
Sengupta, Amitdyuti. "Solidification and Stabilization of Contaminated Soil". ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/538.
Testo completoAbstract (sommario):
In-situ remediation by Solidification and Stabilization (S/S) has shown huge promise in dealing with the clean up of soils contaminated with pollutants listed as Hazardous Substances under Resource Conservation and Recovery Act (RCRA). The site discussed in this paper was contaminated with Naphthalene, heavy metals and other VOCs. In order to find an effective remediation solution it was decided to explore the feasibility of using S/S. Research conducted included exploring Portland cement in combination with organo-clay (bentonite). Admixtures were chosen based on their advantages such as availability, previous experiences, costs and quality assurances. S/S has been found to be an effective method of remediation according to the various past and present Superfund projects. The study plan for this thesis involved bulk analysis and leachability tests to determine the initial and final level of contaminants in the soil and their potential leachability from the soil. The treated soil also underwent weight loss and air emissions (TO-3) tests.
5
Rahmat, Mohamad Nidzam. "Soil stabilization utilising wastepaper sludge ash". Thesis, University of South Wales, 2004. https://pure.southwales.ac.uk/en/studentthesis/soil-stabilization-utilising-wastepaper-sludge-ash(ab24673a-34b7-4f04-a347-3b75a18dc8cf).html.
Testo completoAbstract (sommario):
Increase in environmental awareness over the past decades has resulted in increasing attention to industrial pollution and waste management control. The use of waste is becoming increasingly important in construction. Such materials including Wastepaper Sludge Ash (WSA), can be used to modify certain engineering properties of soils for specific uses to conserve non-renewable natural resources. hi lime-stabilization of sulfate-bearing clay soils, there has been increasing concern over the damage caused by the expansion which is produced when sulfate-bearing soils are encountered. The main objective of this research was to investigate the potential of utilizing WSA, an industrial by-product, as a soil stabilizer with or without blending it with quicklime (CaO), Portland Cement (PC) or with Ground Granulated Blastfurnace Slag (GGBS). The engineering behaviour (plasticity characteristics, compaction, unconfined compressive strength (UCS), linear expansion and California Bearing Ratio (CBR)) of the sulfate-bearing Lower Oxford Clay (LOG) soil and of a non sulfate-bearing soil-industrial Kaolinite (control)-were investigated. Compacted cylinders of LOG and Kaolinite stabilized with quicklime ((CaO) at typical 2wt.%, 4wt.% and 6wt.%) and with various stabilizers incorporating WSA (WSA-Lime, WSA-PC and WSA-GGBS, at 10wt.%, 15wt.% and 20wt.%) were made under controlled laboratory conditions. The cylinders were made under either mellowed (compacted 3 days after mixing) or unmellowed (compacted immediately after mixing) conditions and then moist cured for 7, 28, 90, 180 and 365 days prior to UCS tests. CBR tests were also carried out, but only on selected stabilized LOG samples, at the lowest and highest stabilizer contents. Linear expansion of stabilized cylinders during moist curing and during subsequent soaking was monitored for at least 100 days. The results obtained showed that the blended stabilizers incorporating WSA reduced the plasticity index (PI), reduced the maximum dry density (MDD) and increased the optimum moisture content (OMC) of both LOG and Kaolinite. The UCS values of stabilized systems incorporating WSA for both LOG and Kaolinite were higher than those systems stabilized with the traditional CaO. When WSA was blended with lime, PC or GGBS, the results indicated that in the LOG stabilized system, the strength development of unmellowed samples was generally better than for the mellowed samples. This is in contrast with the Kaolinite stabilized system where it is the mellowed samples that recorded higher strength than the unmellowed samples. The CBR values of the unmellowed samples were also higher than those for the mellowed samples. The linear expansion of unmellowed stabilized LOG system was significantly reduced. This is again quite the opposite in the Kaolinite system, where mellowed samples showed reduced expansion relative to the unmellowed ones. Sulfate and thermogravimetric analysis results suggest that the presence of sulfate in a soil plays a major role in the mellowing process. In conclusion, the findings in this research suggest that whether or not to mellow depends primarily on the stabilizer used. Other variables include the target material and site conditions, besides possibly other factors. There are technological, economic as well as environmental advantages of utilizing WSA and similar industrial by-products, in the stabilization of sulfate bearing and other clay soils, as an alternative to the traditional stabilizers of lime and/or Portland Cement.
6
Li, Xu. "Dual-porosity structure and bimodal hydraulic property functions for unsaturated coarse granular soils /". View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202009%20LI.
Testo completo
7
Chambers, Robert. "Decompaction of a degraded clay soil". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68162.
Testo completoAbstract (sommario):
An experiment was set up at Alfred College, in Eastern Ontario, to investigate methods of correcting the negative effects of deep compaction of fine textured soils.The site was divided into two fields of four treatments with three replicates of each. Treatment 1 was control, treatment 2 subsoiled, treatment 3 compacted and treatment 4 compacted then subsoiled. In year 1 barley was sown in both fields, underseeded with alfalfa in Field 1. The following year alfalfa was grown in Field 1 and corn using minimum tillage in field 2.
Measurements included cone penetration resistance, dry bulk density, and crop yields.
It was found that compaction had a significant effect on lowering yields. However, due to the experiment methodology in the measuring of cone penetration resistance and dry bulk density plus a blocking effect in the corn field, the results were inconclusive statistically as to whether the subsoiling in combination with minimum tillage and alfalfa had an effect of decompacting the soil profile.
8
Kumpiene, Jurate. "Assessment of trace element stabilization in soil". Doctoral thesis, Luleå, 2005. http://epubl.luth.se/1402-1544/2005/38.
Testo completo
9
Vaičikauskaitė, Alfreda. "Arsenic stabilization in step-wise amended soil". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110601_105705-29642.
Testo completoAbstract (sommario):
This master thesis was performed in order to investigate arsenic stabilization in step-wise amended soil. Object of the work - soil which taken from the former wood impregnation industrial site in Forsmo, Sweden. It is contaminated with chromate-zinc-arsenate (CZA). Method of the work - three different amendments were used: zerovalent iron (Fe), fly-ash (FA) and peat (P). The test was performed in three weeks. During the first week, four mixtures (with each single additive and with all together) and blank soil was observed. During the second and third weeks test was performed step-wise adding amendments to soil+Fe mixture. Moisture was kept constant all the time. After each week extractions were made and later investigated by doing electrical conductivity, redox potential and pH tests. For elemental composition ICP-OES analysis was performed. The results of the work - the best result to stabilize arsenic were achieved by adding single iron. Stabilisation using iron, fly-ashes and peat elevated As leaching compared to non-amended soil. Step-wise amendment did not have a significant difference from single amelioration neither to arsenic, nor to other heavy metals investigated.Darbo tikslas - įvertinti pakopinės stabilizacijos poveikį arseno bei kitų sunkiųjų metalų (SM) judrumui užterštame dirvožemyje. Darbo objektas - chromuotu cinko arsenatu užterštas dirvožemis, paimtas iš buvusios medienos apdirbimo aikštelės Forsmo vietovėje, Švedijoje. Darbo metodika - tyrimui buvo naudoti trejopi priedai: geležis (0), lakieji pelenai ir durpės. Tyrimas atliktas per tris savaites. Pirmosios savaitės metu buvo stebimi keturi dirvožemio ir jo priedų mišiniai bei kontrolinis dirvožemio mėginys. Vėliau dirvožemio ir geležies mišinys buvo pakopiniu būdu papildomas lakiaisiais pelenaisi ir durpėmis. Iš visų mišinių padarytos ištraukos ir jose matuojamas elektrinis laidumas, oksidacijos-redukcijos potencialas, pH; atlikta elementinė analizė. Darbo rezultatai - efektyviausiai arseną stabilizuoja geležis. Stabilizacija, naudojant lakiuosius pelenus ir durpes, padidino arseno išsiplovimą iš dirvožemio, lyginant su kontroliniu dirvožemio mėginiu. Pakopinė stabilizacija nebuvo efektyvesnė už vienkartinę stabilizaciją nei arseno, nei kitų tirtų sunkiųjų metalų atžvilgiu.
10
Mu, Tianhong. "Soil Stabilization with Fly Ash and Fibers". OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1301.
Testo completoAbstract (sommario):
In this study, coal combustion by-products mainly fly ash, commercial fibers and a natural fiber i.e., human hair were applied to stabilize the kaolinite clay and local Carbondale soil i.e., silty clay. During recent decades, the demand for infrastructures such as highways, buildings, bridges have greatly increased, especially in the areas where population was growing rapidly. All of these infrastructures need a stable foundation and in many cases the original land couldn't sustain the load from the infrastructures. In such situation, soil stabilization becomes an essential step before the foundation is laid. There are several ways to stabilize soil, viz., mechanical stabilization, chemical stabilization, stabilization by inclusion and confinement etc. It has been reported by several researchers that fly ash and fibers can significantly improve the strength of soil. Fly ash and natural fiber i.e., human hair are both waste materials, and commercial fibers are low-cost compared to other soil stabilizers. In this study, class C fly ash was used to stabilize commercially available clay i.e., Kaolinite; while both human hair and commercially available fibers (e.g., glass fiber and plastic fiber) were used to stabilize Kaolinite and Carbondale local soil. Based on this research, it could be concluded that the class C fly ash can improve the Unconfined Compressive Strength (UCS) value of Kaolinite clay significantly; fibers also could increase the UCS value of both Kaolinite and Carbondale local soil. While, the tensile strength of Kaolinite and Carbondale local soil sometimes increases or decreases depending on the percentages of fiber content used into Kaolinite and Carbondale local soil. The current research on soil stabilization by fly ash and those fibers may provide a new possibility for soil stabilization.
11
So, Tze-chung. "Engineering behaviour of Hong Kong marine clay during vacuum preloading". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41634147.
Testo completo
12
Chandler, Douglas Scott. "An area approach to forest slope stability /". Thesis, Connect to this title online; UW restricted, 1992. http://hdl.handle.net/1773/10181.
Testo completo
13
Zhu, Xiujuan. "Unified constitutive parameters for statically compacted clay /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202008%20ZHU.
Testo completo
14
Llewellyn, C. A. "Practical soil protection and stabilization in Mediterranean viticulture". Thesis, Cranfield University, Cranfield University at Silsoe, 2006. http://hdl.handle.net/1826/1214.
Testo completoAbstract (sommario):
The accelerated erosion of soil by water from Mediterranean hill-slopes under viticulture is a major problem. It is largely a result of the land management techniques employed and their influence on soil protection, structure and stability.
Within this study, the relationships between viticulture practices, soil physical characteristics and erosion processes have been explored in detail, and a soil conservation strategy, which incorporates the use of herbicide managed cover, has been developed.
The strategy was applied and tested in two established vineyards in southern France over a three year period (October 2001 to December 2004). Sediment and runoff losses were monitored at the plot scale from the date of treatment installation and comparisons were made with the losses from plots under conventional soil management.
Cultivation, to produce a fine seedbed for cover establishment, encouraged soil to become hydrophobic and impeded drainage at depth. This aggravated soil losses under saturated conditions and impeded cover establishment. However, total sediment losses were reduced by the presence of a cover at both sites within the monitoring period. The results of a ‘Visual Soil Assessment’ showed that there was a measurable improvement in the physical condition of the soil of the vegetated plot three and a half years after the cover was sown.
Controlled laboratory studies were conducted to identify the most suitable herbicide product and dose rate for inducing dormancy in a grass cover, whilst retaining its protective and stabilizing properties. Two products were tested: Paraquat and Glyphosate. At 21 days after treatment application, the treatment effects on plant and soil physical characteristics were assessed. Herbicide product and dose were found to indirectly influence a soil’s potential to erode but more detailed studies are required. Initial results suggest that Paraquat is the more suitable of the two products tested.
The study concluded that herbicide managed permanent cover is a practical option for soil conservation in Mediterranean viticulture.
15
Doohan, Thomas James. "Drivers of Soil Organic Matter Stabilization across Ohio". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1597941993038872.
Testo completo
16
Ishihara, Katsuji. "At-rest and compaction-induced lateral earth pressures of moist soils". Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07122007-103943/.
Testo completo
17
Kokesh, Christopher Michael. "Bio-engineering for land stabilization". Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1243971701.
Testo completo
18
Ahmed, Naif Baker. "The stabilization of Aeolian sand dunes". Thesis, Durham University, 1990. http://etheses.dur.ac.uk/1099/.
Testo completo
19
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.
Testo completoAbstract (sommario):
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.
20
Venkata, Swamy B. "Stabilisation Of Black Cotton Soil By Lime Piles". Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/219.
Testo completoAbstract (sommario):
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.
21
Ramachandran, Asha Latha. "Investigation on bacterial biopolymers and biominerals for soil stabilization". Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/84787.
Testo completoAbstract (sommario):
The practice of soil stabilization has become an essential part of present day geotechnical engineering
projects. However, it is a matter of growing concern that popular chemical stabilizers possess high carbon
footprint and adversely affect the eco-system. With the emergence of bio-geotechnology as an
environmentally benign alternative to chemical stabilization, there is a paradigm shift in the field of soil
stabilization. This thesis is a novel attempt to underpin the effect of bacterial biopolymers and
biomineralisation on stabilization of soil.
22
Trenner, Brian Robert. "Bioengineering for Land Stabilization". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253549875.
Testo completo
23
Tatarniuk, Catherine. "Deep soil mixing as a slope stabilization technique in Northland Allochthon residual clay soil". Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2014. http://hdl.handle.net/10092/9648.
Testo completoAbstract (sommario):
Road slips are common in Northland Allochthon residual clay soil, and are commonly mitigated using deep soil mixing (DSM). A deficiency in laboratory investigations on Northland Allochthon residual clay and a need for a better understanding of the numerical modelling of DSM columns used to mitigate unstable slopes in this soil type is evident in literature, and has been highlighted by practitioners. This research has aimed to fill aspects of these deficiencies.
Field testing and classification tests have provided insight into how the soil varies between sites and with depth, and how in situ testing methods compare to one another. Field testing has also demonstrated that soil property changes around DSM columns have been shown to exist through seismic flat plate dilatometer testing before and after column installation, which has not previously been proven using an in situ method. This is important for practitioners who use DSM to demonstrate the additional soil improvements provided by the columns.
The testing of reconstituted soil is fundamental in examining soil behaviour, and this study is the first to examine the triaxial behaviour of reconstituted specimens of Northland Allochthon soil. Laboratory triaxial testing and oedometer testing have allowed for a normalized comparison of the intact strength of Northland Allochthon residual clay soil to its reconstituted state. This work provides an answer to the important question regarding the role of soil structure in this soil type. It was revealed that soil structure results in increased shear strength of the soil, and that this increase is primarily cohesive in nature. The near coincidence of the post-rupture strength of intact specimens with the critical state angle of internal shearing resistance provides support for its use in examining first time slope failures in this soil type. This is an important finding for practitioners, as it demonstrates the value of testing reconstituted specimens, which are much easier to obtain than high quality intact specimens. In addition, relationships between the plasticity index (PI) of the soil and certain soil parameters (and soil behaviour) have been demonstrated to be relevant and useful for this soil type.
Soil properties acquired in this study were tabulated along with those from other field sites in Northland Allochthon soil. It was found that there is significant variation between field sites, likely due to varying degrees of weathering, which is an important consideration for practitioners dealing with this soil type.
A brief examination of constitutive models for representation of Northland Allochthon residual clay soil have shown that several different models can sufficiently represent the behaviour of this soil. The Mohr-Coulomb model was selected for use in subsequent finite element numerical models. A case study of a road slip at a field site in Northland Allochthon residual clay soil, mitigated using DSM columns, revealed that the use of a pre-existing slip surface after first time failure leads to an improved match between observed field behaviour and the behaviour of the slope as exhibited in a numerical model. This type of failure mechanism has not been previously examined in this soil type, and this case study demonstrates it is a useful approach that should be considered when dealing with second time failure in Northland Allochthon slopes. This numerical model also introduces the replacement ratio method (RRM), a technique used to represent the three dimensional (3D) geometry of the DSM columns in the more commonly used two dimensional (2D) analysis.
Examination of laterally loaded DSM columns in plan view, which has not previously been performed in the context of DSM columns, has illustrated how installation effects and column shape influence load displacement curves, and demonstrates the effects of soil arching. This analysis provides practitioners with evidence that improved soil property changes, found to occur around DSM columns, lead to improved DSM column performance. A simplified 3D numerical model of laterally loaded DSM columns, which builds on the ideas developed in the previous two 2D models, has been compared to an identical 2D model. It is shown that the commonly used RRM results in an overestimation of the resisting force provided by the columns as compared to the 3D model. However, this does not necessarily imply that the use of the RRM in an analysis will always result in a safe slope. The degree to which its use will affect the results will depend on the slope geometry, location of the DSM columns, and the type of analysis performed (i.e. factor of safety or deformation based). A modification to the RRM has been proposed. It is recommended that when the DSM column diameter and soil properties are similar to those used in this study, the MRRM developed in this study should be utilized. In circumstances where they differ, it is recommended that practitioners perform a sensitivity analysis using the MRRM developed here as a basis for modifying the RRM in order to determine the extent to which their results are influenced. If the influence is significant, the use of a 3D model should be considered.
24
Sariosseiri, Farid. "Critical state framework for interpretation of geotechnical properties of cement treated soils". Online access for everyone, 2008. http://www.dissertations.wsu.edu/Dissertations/Summer2008/f_sariosseiri_070208.pdf.
Testo completo
25
Pang, Mei-yee. "The nature and magnitude of soil compaction in different human-modified habitats in Hong Kong". Click to view the E-thesis via HKUTO, 2001. http://sunzi.lib.hku.hk/hkuto/record/B42576520.
Testo completo
26
Ba, Te. "Flow of air-phase in soils and its application in emergent stabilization of slopes /". View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20BA.
Testo completoAbstract (sommario):
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 170-180). Also available in electronic version. Access restricted to campus users.
27
Hunter, Gavan James Civil & Environmental Engineering Faculty of Engineering UNSW. "The pre- and post-failure deformation behaviour of soil slopes". Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2003. http://handle.unsw.edu.au/1959.4/19108.
Testo completoAbstract (sommario):
This thesis examines the pre and post failure deformation behaviour of landslides in cut, fill and natural soil slopes, and of the deformation behaviour of embankment dams. The deformation behaviour of landslides and embankment dams have been analysed from a database of case studies from a number of classes of slope (and dam) and material type. The database included some 450 landslides in cuts, fills and natural slopes, and some 170 embankment dams. For landslides in soil slopes, methods and guidelines have been developed for use in the analysis, evaluation and prediction of the pre and post failure deformation behaviour. They take into consideration the factors influencing and the mechanics controlling the deformation behaviour for the classes of slope and material types, which are different for pre and post failure. Pre-failure deformations are largely controlled by the effective stress conditions within the slope, changes in the boundary conditions and the response of the soil to those changes in boundary conditions. Whether the soil, under the effective stress conditions imposed within the slope, is contractive (and saturated or near saturated) or dilative on shearing, has a significant influence on the pre failure deformation behaviour. The post failure deformation behaviour is strongly influenced by the mechanics of failure (including whether the soil is contractive or dilative on shearing), the source area slope angle, the downslope geometry, the orientation of the surface of rupture, the material properties and slide volume. Guidelines are presented for prediction of 'rapid' and 'slow' post failure velocity. For embankment dams, methods and guidelines have been developed for evaluation and prediction of the deformation behaviour during and post construction for selected embankment types. They take into consideration the influence of material type and placement methods, material strength and compressibility properties, embankment zoning geometry, embankment height, and reservoir operation, amongst other factors. Guidelines have been developed to assist in the identification of 'abnormal' deformation behaviour, which can be related to internal deformations or a marginal stability condition and the onset to failure.
28
Adalier, Korhan. "Mitigation of earthquake induced liquefaction hazards". online access from Digital Dissertation Consortium access full-text, 1996. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?9635658.
Testo completo
29
Jegandan, Seevaratnam. "Ground improvement with conventional and novel binders". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608950.
Testo completo
30
Peterson, Jennifer Lynn. "Probability analysis of slope stability". Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1070.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains viii, 91 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 63-64).
31
Liu, Ying. "Limit equilibrium methods for slope stability analysis". Click to view the E-thesis via HKUTO, 2002. http://sunzi.lib.hku.hk/hkuto/record/B42576684.
Testo completo
32
Molope, Mishack Bochankge. "Some effects of biological and physical processess on soil aggregate stability". Thesis, University of Stirling, 1985. http://hdl.handle.net/1893/2595.
Testo completoAbstract (sommario):
The effects of biological and physical processes on the aggregate stability of some weakly structured arable and pasture soils were investigated. Preliminary investigations showed significant correlations between soil organic matter and both wet sieving and turbidimetric methods of aggregate stability; the latter method was chosen on grounds of convenience. Scanning electron microscope pictures showed the presence of both fungi and bacteria when soils were incubated. Growth of fungi, estimated by ergosterol measurement, correspond to temporary stability increases, which could be explained by retention of soil particles within the reticulum of fungal hyphae. The effect disappeared as the fungi were destroyed and replaced by bacteria and actinomycetes. Effects caused by fungi were examined separately, using vancomycin to inhibit bacterial growth, and bacterial effects by using cycloheximide to eliminate fungi. Bacterial growth had little direct effect in stabilising soil aggregates; periodate oxidation showed that polysaccharides produced by bacteria are mainly responsible. To examine the contribution of physical processes to increased stability in remoulded soils biological processes were eliminated by sterilisation. Thixotropic changes made a contribution to age hardening in remoulded aggregates similar in magnitude to biological processes. Thixotropic changes were reversible and accompanied by soil strength and metric water potential changes. Polysaccharides did not contribute to thixotropic aging processes. Remoulded soils were subjected to wetting/drying and freezing/thawing cycles. After 3 to 6 cycles the stability of both sterilised and unsteriliserd soils recovered to that of natural aggregates, suggesting a contribution by thixotropy. Repeated weathering cycles decreased the stability of unsterilised, and more so sterilised, field aggregates suggesting that in the former, bond reformation due to biological activity counteracted the destruction caused by wetting/drying and freezing/thawing.
33
Jaapar, Abd Rasid Bin. "A framework of a national slope safety system for Malaysia". Thesis, Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37384600.
Testo completo
34
Wong, Siu-wai. "Plant selection for revegetation projects in Hong Kong". Click to view the E-thesis via HKUTO, 1992. http://sunzi.lib.hku.hk/hkuto/record/B43893442.
Testo completo
35
Huang, Ying. "Treatment of PCB-contaminated soil by stabilization and solidification processes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39663.pdf.
Testo completo
36
Lee, Chun-fai Julian. "Soil nailing a robust design for joint-controlled weathered rock in Hong Kong /". Click to view the E-thesis via HKUTO, 2003. http://sunzi.lib.hku.hk/hkuto/record/B42577214.
Testo completo
37
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.
Testo completoAbstract (sommario):
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.
38
Thomas, Bari Ian. "Stabilisation of sulphide rich soil : problems and solutions". Thesis, University of South Wales, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269056.
Testo completo
39
Jonsson, Carl. "Deep stabilization with Cement Columns : A Laboratory Studie". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62252.
Testo completo
40
Pathmanathan, Marie Leony. "Numerical simulation of the performance of horizontal drains for subsurface slope stabilization". Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/m_pathmanathan_011309.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in civil engineering)--Washington State University, May 2009.Title from PDF title page (viewed on July 27, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 82-84).
41
Karami, Azzam Omar 1962. "Consolidation of clays using the triaxial apparatus". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276842.
Testo completoAbstract (sommario):
The calculation of a consolidation settlement is an important problem encountered in the foundation of buildings. Due to need for simplicity engineers are mainly using the one dimensional theory of Terzaghi for calculations of consolidation settlements with time. Consolidation tests are still performed in most laboratories with the traditional oedometer cell. Although the results of the oedometer can provide relatively reliable results, they are not equally effective for the calculation of the rate of consolidation. This primarily because of the inability of the oedometer cell to obtain full saturation of the sample. To ensure full saturation, back pressure must be applied which is not possible for conventional oedometer cell. The alternative use of the triaxial cell to examine the consolidation behavior of soils is discussed here.
42
Nciizah, Adornis Dakarai. "Cattle manure, scalping and soil wetness effects on some physical properties of a hardsetting soil and associated early maize growth". Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/349.
Testo completoAbstract (sommario):
Most soils in the Eastern Cape Province, South Africa are shallow and are low in organic matter. Therefore these soils are structurally fragile and highly susceptible to inherent degradative processes like hardsetting. The objective of this study was to determine the effect of cattle manure, scalping and soil wetness on aggregate stability, penetration resistance and early maize growth in hardsetting soils. Glasshouse and field studies were conducted to determine the effect of cattle manure on aggregate stability and penetration resistance of freshly exposed topsoils by scalping at 0, 10 and 20 cm depths. In the glasshouse cattle manure was applied at 0 and 20 Mg/ha and matric suction was kept at ~ 30 and ~ 400 kPa; contrasting high and low soil wetness. Three soils were put in pots and arranged in a randomized complete block 3 2 2 factorial design. The field study was done at the University of Fort Hare research farm and the treatments were arranged in a split-plot complete randomized design with three replications. Scalping treatment was the main plot whilst the quantity of the cattle manure applied was the sub plot. Cattle manure increased mean weight diameter (MWD) by between 48% and 71% under glasshouse and between 18% and 33% under field conditions, depending on the soil wetting rate. Cattle manure reduced MWD when the soil under field condition was subjected to mechanical shaking. Soil penetration resistance decreased linearly, with increasing soil wetness but it rapidly increased with increase in matric suction up to ~200 kPa and thereafter the rate of increase reduced. In the glasshouse, all treatments had no significant effects on shoot dry weight but low matric suction increased root dry weight by 133%. Interaction of cattle manure and low matric suction reduced shoot length by 6%, shoot fresh weight by 25%, root surface area by 36%, root length by 5% and root fresh weight by 29% compared to the control. In contrast, application of cattle manure and high matric suction increased shoot length by 37%, shoot fresh weight by 136%, root surface area by 159%, root length by 94% and root fresh weight by 119%. In the field, cattle manure application increased root length density and shoot dry matter by 26% and 30% respectively. Cattle manure improved the stability of aggregates of the hardsetting soil under rapid or slow water intake conditions experienced during rainfall or irrigation. However, under field conditions cattle manure acted as a deflocculant and decreased the stability of aggregates when mechanical stress was applied. The effectiveness of cattle manure in improving maize growth in hardsetting soils was determined by matric suction.
43
Zhang, Li Zhi. "Application of Bayesian model class selection on differential problems in geotechnical engineering". Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2590616.
Testo completo
44
Murray, John J. "Enhancing soil behavior through reinforcement with discontinuous recycled fiber inclusions". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/32766.
Testo completo
45
Saleh, Atef A. "Evaluation of geosynthetic reinforcement for long-term stability of embankment slopes /". Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Testo completo
46
Asoudeh, Atefeh. "Identifying Residual Soil Parameters for Numerical Analysis of Soil Nailed Walls". Thesis, Griffith University, 2016. http://hdl.handle.net/10072/367048.
Testo completoAbstract (sommario):
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
Full Text
47
Söderlund, Olov. "Stabilization of Soft Soil with Lime and PetritT-An Experimental Study". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70912.
Testo completo
48
Smedborn, Pausson Eva. "Chemical Stabilization of Arsenic in Contaminated Soil under Low Redox Conditions". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72340.
Testo completoAbstract (sommario):
Remediation techniques for arsenic contaminated soil have previously focused mostly on the surface soil layers where aerobic conditions are prevalent. In this master thesis, chemical stabilization by adding zero-valent iron (Fe(0)) and calcium oxide (CaO) to an arsenic-contaminated soil under low redox conditions have been studied through up-flow percolation tests. Over a time of 2 months, pH, conductivity, redox potential and concentrations of major and minor elements including As, Zn, Cu, Cd, Fe and Ca under both fluctuating and continuous flow were measured. Results indicate that CaO is a very promising amendment to use under conditions of low redox, immobilizing 98% of the As and 50-65% of Zn, Cd and Cr over the 8 weeks of testing, compared to the untreated soil. Copper on the other hand was mobilized by the treatment; but as the concentrations of Cu in the soil was low the increased leaching would in this case not be problematic. The leached water also had a very alkaline pH at 13, while conductivity was relatively high at 6.5 mS cm-1 and the redox potential remained negative throughout the two months. Geochemical modelling indicate that the immobilization of As is most likely controlled by precipitation of Ca-As-complexes as well as ettringite and portlandite. The precipitation of these minerals are controlled by pH, while redox conditions were shown to not be a controlling factor. The alkalinity of the CaO-amended soil was very high and it is expected that the alkaline conditions controlling the immobilization of As will prevail for hundreds of years. Fe(0) that previously has shown good results in stabilizing As under oxidized conditions did not effectively immobilize As under the low redox conditions in this study. Rather, the leaching of As and metals like Cr, Cd, Cu and Zn showed very similar results as the untreated soil. The results signifies the importance of activating the Fe(0) beforehand to allow amorphous Fe-oxides to form to which the metal(loids) can sorb to. In the study it was also observed that a fluctuating groundwater table could have an effect on both untreated and treated soil as wet and dry cycles influenced the leached concentrations of As and many other elements. More As was leached during the dry days in the untreated soil and the soil treated with Fe(0), while the opposite was true for the CaO-treated soil. The results suggests that using CaO as an amendment to treat As-contaminated soil is a method that potentially can be used for soils that have low redox conditions, for example soils below the groundwater table and landfills, although caution should be used in situations with more complex contamination, e.g. where both As and Cu are present.Efterbehandlingsmetoder för arsenikförorenad jord har tidigare fokuserat på ytliga jordlager där syre finns tillgängligt och förhållandena är oxiska. I denna masteruppsats har kemisk stabilisering av arsenik under anoxiska förhållanden i en förorenad jord studerats. I perkolationsförsök över två månader har effekten av två olika kemiska tillsatser, nollvärt järn (Fe(0)) och kalciumoxid (CaO), på utlakningen av halvmetaller och metaller som As, Zn, Cd, Cu och Cr samt påverkan på pH, konduktivitet och redoxpotential undersökts under både fluktuerande och konstanta flöden. Resultaten visar att CaO är en lovande tillsats att använda för kemisk stabilisering av As i jordar som har anoxiska förhållanden. 98% av As immobiliserades jämfört med den obehandlade jorden. Behandlingen med CaO resulterade även i ett stabilt basiskt pH på 13. Konduktiviteten hölls också på en stabil nivå på 6,5 mS cm-1 medans redoxpotentialen varierade en del men var negativ under hela experimentet. Den utlakade koncentrationen av As låg mellan 0.059 och 0.021 mg L-1. CaO immobiliserade även Zn, Cd och Cr med en effektivitet som låg mellan 50-65%, jämfört med den obehandlade jorden. Koppar däremot mobiliserades och lakades ut i större utsträckning; men då Cu-koncentrationen i jorden var låg från början utgör detta inget större problem. Geokemisk modellering indikerade att immobiliseringen av As kontrolleras av pH, men förblev opåverkad av redoxpotentialen. Då alkaliniteten i den CaO-behandlade jorden var hög förväntas de basiska förhållandena som kontrollerar den kemiska stabiliseringen av As att kvarstå under flera hundra år. Tidigare studier har visat att Fe(0) till stor del stabiliserar As under oxiska förhållanden, men under de anoxiska förhållandena i denna studie hade den Fe(0)-behandlade jorden liknande resultat som den obehandlade jorden, både vad gäller utlakning av metaller, pH, konduktivitet och redoxpotential. Detta markerar vikten av att aktivera Fe(0) genom att låta den reagera med syre och vatten i jorden för att bilda amorfa Fe-oxider som (halv)metallerna kan adsorbera till. I detta fall tillsattes inget vatten i förväg, vilket ledde till att det mesta av järnet lakades ut direkt, utan att bilda fler ytor som speciellt As kan binda till. För båda dessa jordar var utlakningen av As två storleksordnar större jämfört med den CaO-behandlade jorden. Studien visade också att en fluktuerande grundvattennivå kan ha en effekt på utlakningen av grundämnen både behandlad och obehandlad jord, då cykler av anoxiska och oxiska förhållanden påverkade koncentrationerna i utlakningsvattnet. Mer As lakades ut under de dagar som hade mer anoxiska förhållanden jämfört med oxiska dagar för den Fe(0)-behandlade jorden och den obehandlade jorden, medans det motsatta var sant för den CaO-behandlade jorden. Resultaten indikerar att CaO har en potential till att användas för att kemiskt stabilisera As i jordar som har låga redox-förhållanden, exempelvis i jordar som är under grundvattenytan och i deponier, men att försiktighet ska användas i jordar som har en mer komplex föroreningssituation, speciellt i jordar som är förorenat av både As och Cu.
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Maffettone, Roberta. "Stabilization/solidification processes for the treatment of contaminated soil and waste". Doctoral thesis, Universita degli studi di Salerno, 2015. http://hdl.handle.net/10556/1753.
Testo completoAbstract (sommario):
2013-2014Recovering industrial waste and contaminated soil is one of the main objectives in environmental management. Nowadays in Italy, landfilling is responsible for up to 40% of total soil contamination and up to 50% of the used remediation techniques involves excavation and disposal. On the other hand, the European Legislation has set key drivers to improve waste management, as setting recycling targets and limiting the use of landfilling with its rising cost. In this scenario, new technologies to reduce the toxicity of contaminated soil and hazardous waste before their disposal or to reuse them as aggregates are of great interest. Stabilisation/solidification (S/S) is a treatment for wastes and soils which mainly uses cementitious or pozzolanic binders to produce a solid monolith that incorporates the contaminants. This process is particularly effective on heavy-metals contaminated soils. Other additives/fillers can also be used during a pre-treatment phase to amend adverse chemical and physical characteristics, e.g. high moisture content. Alternative methods to treat contaminated waste and soil exploited the application of accelerated carbonation to cement-based S/S. This process can improve the characteristics of the stabilized products in terms of leaching, strengths or pH. Accelerated carbonation (ACT) is an enhanced form of natural carbonation that has been developed during the last years at industrial scale for the treatment of contaminated soil and industrial wastes. Accelerated carbonation induces a rapid reaction exposing the mineral or the reactive waste to a controlled atmosphere containing CO2 and promotes rapid hardening of the product. The resultant precipitation of calcium carbonate reduces the porosity of the material, and leads to further changes at the microstructure, aiding the retention of contaminants and improving the mechanical properties. The pH is also lowered with the result of reduced solubility of many heavy metals. Waste can be formed into aggregate by agglomeration. If the two processes are combined, it is feasible to produce hardened aggregate. The final product can be reused as aggregate in engineering fill or in concrete production. The aim of the research project conducted during the Ph.D. programme is the development of an innovative approach for the enhancing of stabilization/solidification treatment of contaminated soils and wastes. The research aimed at the identification of innovative formulation using cement and thermal wastes for heavy-metals contaminated soil treatment and at the investigation of the effect of the accelerated carbonation applied to cement-based stabilization/solidification. Tests of cement-based stabilization/solidification using Portland cement and the effect of accelerated carbonation on metals mobility were investigated on artificial heavy-metals contaminated soil at the Sanitary Environmental Engineering Division (SEED) at the University of Salerno. The process was assessed with further investigations on soil washing residues blended with thermal ashes and cement for the production of lightweight recycled aggregate. This part was conducted within the LLP Erasmus Placement Programme at the Centre for Contaminated Land Remediation (CCLR) of the University of Greenwich (UK). The process investigated entailed the mixing of soil washing residues with paper incineration ashes, reactive to carbon dioxide, or sewage sludge ashes followed by accelerated carbonation to produce the aggregate. Portland cement was used as the binder, which also has an ability to combine with CO2. The effect of accelerated carbonation on the cemented contaminated soil was evaluated by mineralogical and structural properties. Chemical stability was measured by leaching of heavy metals from the raw materials and the final products. The aggregates produced showed comparable strength to commercially lightweight aggregates. Accelerated carbonation increased the strength and the density of the aggregate compared to the hydrated one. Heavy metals leaching were substantially unaffected by carbonation, apart for copper and barium. Further investigation tested the aggregates for using in lightweight concrete block and for green roofing. The use of a synthetic CO2 flue gas lead to a capture of the carbon dioxide leading to a “low carbon” product. The study showed the applicability of the process for manufacturing lightweight aggregates from soil washing residues and ashes by enhanced cement based S/S as a good alternative for a wide range of civil engineering applications. The effect of accelerated carbonation has to be further explained. Future investigations are needed to enhance the process based on the variability of the wastes. Other waste and alternative carbon dioxide reactive fillers can be considered to be treated by the process. [edited by author]
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50
Negim, Osama. "New Technique for Soil Reclamation and Conservation: In Situ Stabilization of Trace Elements in Contaminated Soils". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2009. http://tel.archives-ouvertes.fr/tel-00408020.
Testo completoAbstract (sommario):
L'accumulation de métaux toxiques dans le sol est principalement héritée de matériaux parents ou d'éléments résultant de l'activité humaine. Par conséquent, de nouvelles techniques sont en cours d'élaboration pour remédier à ces contaminations dans les sols pollués, telles que la phytoremédiation et la stabilisation in situ. La stabilisation in situ est une technique commune de réduction des effets négatifs des métaux et métalloïdes, tels que As, Cr, Cu, Cd et Zn dans les sols contaminés par l'ajout d'amendements. L'application de matières alcalines telles que les laitiers d'aciéries et un laitier modifié enrichie en phosphates dans le sol constitue un outil prometteur pour la réduction de la mobilité et la biodisponibilité des éléments traces dans les sols contaminés ainsi que pour l'assainissement du sol et l'amélioration de ses propriétés physique, chimique et minéralogique, ainsi que la production végétale.