Dissertations / Theses on the topic 'Cohesive soils'
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1
Mobley, Thomas Jackson Melville Joel G. "Erodibility testing of cohesive soils." Auburn, Ala, 2009. http://hdl.handle.net/10415/1776.
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Mattar, Joe. "An investigation of tunnel-soil-pile interaction in cohesive soils /." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112577.
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Underground tunnels are considered to be a vital infrastructure component in most cities around the world. Careful planning is always necessary to ensure minimum impact on nearby surface and subsurface structures. This thesis describes the experimental and numerical investigations carried out at McGill University to examine the effect of existing pile foundation on the stresses developing in a newly constructed tunnel supported by a flexible lining system. A small scale testing facility was designed and built to simulate the process of tunnel excavation and lining installation in the close vicinity of pre-installed piles. Lining stresses were measured for different separation distances between the tunnel and the existing piles. Significant decrease in circumferential stresses was observed when the lining was installed at a distance that ranges between one to three times the tunnel diameter from the piles. Two-dimensional finite element analyses were also conducted to investigate the different aspects of the pile-soil-lining interaction including lining deformation, axial forces and bending moments. The measured lining stresses agreed with those obtained using finite element analysis. The results presented in this study provided an insight into understanding an important aspect of this soil-structure interaction problem.
3
Kim, Dong Gyou. "Development of a constitutive model for resilient modulus of cohesive soils." Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078246971.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xxvi, 252 p.; also includes graphics. Includes abstract and vita. Co-advisors: Frank M. Croft and Tarunja S. Batalia, Dept. of Civil Engineering. Includes bibliographical references (p. 122-131).
4
Beadle, Michael E. "Settlement induced by tunnelling in cohesive-frictional soils." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21081.pdf.
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Mostafa, Khaled F. "Numerical Modeling of Dynamic Compaction in Cohesive Soils." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1286904792.
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Aubeny, Charles Paul. "Rational interpretation of in-situ tests in cohesive soils." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13198.
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Kwok, Leung Cheung. "A study of cohesive-frictional soils under dynamic loading." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201916.
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Many previous studies have been focused on the behaviour homogeneous granular soils under the quasi-static loading, however, various soil types exist in the field. Therefore, based on the evaluation of these previous studies, an extensive study has been addressed to expose the dynamic behaviour of cohesive-frictional soils associated with the effects of fines content, the effect of moisture content and the type of impact regime. The proposed study mainly investigates the behaviour of sand – clay mixtures to impact loading, both from a loaded plate dropped from different heights and one dropped repeatedly from a fixed height. The Aberdeen beach sand and the Teuchan clay were used for the study and mixed in different proportions to create soils of varying proportions. The six soil samples used have known volumetric proportions of sand : clay and the tests were carried out under the dry condition and two other moisture contents. The results determine the optimal percentage of fines content and its related moisture condition to obtain more stable performance of the granular soils under dynamic compaction. It can be implemented to enhance the quality of ground improvement techniques for the construction. A Soil Model Tester for 2-Dimension program (SM2D) [Chan (1988)] was used to modify the existing material model before being used for Finite Element simulation. The impact test results were used to verify the numerical model developed using an explicit u-w schemebased finite element program, GLADYS2E [Chan et al. (1992, 1994)]. Such use of explicit schemes requires the use of time step lengths which are smaller than a critical value, in order that stability and accuracy of solution are ensured. A semi-empirical formula has been developed for the critical time step determination using MATLAB.
8
Taylor, Paul. "Fast shearing of cohesive soils using ring shear apparatus." Thesis, University of Warwick, 1998. http://wrap.warwick.ac.uk/102336/.
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Residual shear strength is a fundamental property of cohesive soils and is the governing parameter in many slope stability problems, particularly the reactivation of landslides. Traditionally, residual strengths are determined in the laboratory at slow drained rates of shearing using either shear boxes with reversals or ring shear apparatus. Many catastrophic landslides have been triggered by seismic loading inducing fast rates of shear. Interest has therefore developed in laboratory shear testing at faster rates and over greater displacements to establish fast residual shear strengths. This thesis presents results from testing using the Imperial College-Norwegian Geotechnical Institute Ring Shear Apparatus modified to conduct shearing at velocities up to 1 m/min. The variation of residual strengths as shear rate increases is investigated in association with soil grading and plasticity and also with the morphology of the shear zone. A novel set of undulating interfaces are used to investigate the influence of shear zone waviness. The research concludes that as shear rate is increased three types of fast residual shear strength variation may occur: (i) little variation from the slow residual shear strength, (ii) a continuous increase above the slow residual shear strength or (iii) an initial increase followed by a decrease to levels significantly below the slow residual shear strength. Increases in fast strength are attributed to particle disorientation and viscous effects. Falls in fast residual shear strength are attributed to the generation of positive pore water pressure in the shear zone, as a result of a pumping effect induced by wavy or inclined shear zones. Computational modelling of this pumping effect is undertaken using consolidation theory. Fast peak strengths and slow peak strengths after fast shearing are also investigated. Finally, the influence on slow residual shear strength of shear zones with undulations parallel to the shear direction are studied both mathematically, and using the Bromhead Ring Shear Apparatus.
9
Salem, Hicham. "A Practical Approach to the Erodibility of Cohesive Soils." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39673.
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A set of solutions to the cohesive soil erosion problem were developed through this study.
A first device, the Erosionometer, was developed to perform a quick and reliable test to determine the critical shear stress of soils. The Erosionometer is based on physical shearing of the soil surface and has been calibrated through comparison with piston flume measurements of critical shear stress for entrainment of various fluvial bed sediments. This device is portable, easy to deploy in the field and in the laboratory and allows engineers and researchers to cover a sizeable terrain by performing many tests in a short timeframe, with immediate results. A modification to the Erosionometer was made to allow for subjecting the soil sample to a pressure differential while testing for critical shear stress. The added functionality is intended for investigating the effect of pressure gradient on the erodibility of cohesive soils by allowing for the erosion test to be conducted under a high pressure head while the other face of the sample (away from the flow) is maintained at zero head. Testing demonstrated that a positive pressure gradient on the eroding side (high pressure on flow side) can significantly increase the critical shear stress of cohesive soils, which is in line with other research available in the literature. The results show a simple linear relation between pressure differential and critical shear stress. Practical implications of these results are discussed.
A second device, the Erosion Rate Meter, or ERM, was developed to test cohesive soil samples to determine the rate of erosion under various levels of bed shear stress. This device, while being portable and fast to setup and run, is a very realistic simulation of the flow-bed interaction and allows for a direct measurement of bed shear stress on the soil sample and a precise measurement of the erosion rate. An obvious outcome of using the ERM is the easy development of erosion rate vs. bed shear stress relationships or models to characterize the different soils for design projects or further research. Of the 16 tested cohesive soils, all but two demonstrated a linear relation between erosion rate and bed shear stress.
The testing systems and methods developed in this research provide a comprehensive solution to the erodibility of cohesive soils from investigation to design. Significant improvements are achieved over existing systems in the speed, reliability, accuracy, and cost of estimating the erodibility of cohesive soils.
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Akinola, Akinrotimi Idowu. "Temporal and Thermal Effects on Fluvial Erosion of Cohesive Streambank Soils." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96768.
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In the United States, the annual cost of on-site soil erosion problems such as soil and nutrient losses, and off-site soil erosion problems such as sedimentation of lakes and river, loss of navigable waterways, flooding and water quality impairment, has been estimated at 44 billion USD (Pimentel, 1995; Telles, 2011). While eroding sediment sources can either be from land or from stream/river systems, the erosion from streambanks can be quite significant, reaching up to 80% of sediment leaving a watershed (Simon et al 2002; Simon and Rinaldi 2006). Despite many decades of research one the erosion of cohesive soils by flowing water (fluvial erosion), this significant aspect of environmental sustainability and engineering is still poorly understood. While past studies have given invaluable insight into fluvial erosion, this process is still poorly understood. Therefore, the objective of this dissertation was to examine the relationship between time and erosion resistance of remolded cohesive soils, and to quantify and model the effects soil and water temperature on the fluvial erosion of cohesive soils
First, erosion tests were performed to investigate how soil erosion resistance develops over time using three natural soils and testing in a laboratory water channel. Results showed that the erosion rate of the soils decreased significantly over the time since the soils were wetted. This study indicates researchers need to report their sample preparation methods in detail, including the time between sample wetting and sample testing.
Second, erosion tests were performed at multiple soil and water temperatures. Results showed that increases in water temperature led to increased erosion rates while increases in soil temperature resulted in decreased erosion rate. When soil and water temperatures were equal, erosion results were not significantly different. Results also showed a linear relationship between erosion rate and the difference between soil and water temperatures, indicating erosion resistance decreased as heat energy was added to the soil.
Lastly, two common erosion models (the excess shear stress and the Wilson models) were evaluated, and were modified to account for soil and water temperature effects. Results showed that, compared to the original models, the modified models were better in predicting erosion rates. However, significant error between model predictions and measured erosion rates still existed.
Overall, these results improve the current state of knowledge of how erosion resistance of remolded cohesive soils evolves with time, showing the importance of this factor in the design of cohesive erosion experiments. Also, the results show that by accounting for thermal effects on erosion rate, the usability of erosion models can be improved in their use for erosion predictions in soil and water conservation and engineering practice.PHD
11
Hairsine, Peter Brian, and n/a. "A Physically Based Model of the Erosion of Cohesive Soils." Griffith University. Division of Australian Environmental Studies, 1988. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050826.114613.
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A new model of the erosion by water of cohesive soils is developed using physical principles. The theoretical framework which is developed recognises the changing nature of the eroding surface of a soil. Raindrop impact and overland flow are considered to act upon a soil surface so removing soil from the cohesive original (or parent) soil. Once this soil enters the overland flow, either as aggregates or primary particles, it is considered to return to the soil bed, from which it may be re-removed. The development of a deposited layer makes it necessary to distinguish between processes removing sediment from the original soil and those processes removing the deposited layer. This layer, being formed by the relatively gentle action of deposition during the current erosion event, is presumed cohesionless. The physical properties of the original soil and the deposited layer are considered to be very different. The development of two experimental apparatus, a rainfall/runoff simulator and a settling tube for the measurement of aggregate settling velocities, is first described. Experimental investigations, using these apparatus, and field observations to inform the description of the erosion and deposition processes, are then presented. The processes by which rainfall impact removes sediment from the original soil and the deposited layer are termed rainfall detachment and rainfall re-detachment respectively. Initially, descriptions of these processes in the presence of deposition, are combined in a model describing net rainfall detachment when removal of sediment from the flow bed by overland flow is not occurring. The developriient of the deposited layer is considered both quantitatively and qualitatively. The solution of the equation describing mass conservation is then given for the equilibrium situation when the mass of the deposited layer, and therefore the sediment concentration, is constant with respect to time. The processes by which overland flow removes sediment from the original soil and the deposited layer are termed entrainment and re-entrainment. The work done by the process of entrainment is considered to be done wholly against the cohesive strength of the original soil. In contrast to the process of entrainment, the work done in re-entraining sediment from the deposited layer is considered only to be done against gravity. The resulting description of these processes is then combined with the previous descriptions of rainfall detachment, rainfall re-detachment and deposition and with the equation describing the conservation of mass of sediment within any arbitary number of size (or settling velocity) classes. A plane geometry model Is developed in which the surface water flow is considered to be uniformily distributed across a plane slope on which all processes act. When the mass of the deposited layer is steady, two possible forms of equilibrium are shown to exist. When the coverage of the original soil by deposited layer is partial, the sediment concentration is limited by the removal of the cohesive original soil by entrainment and rainfall detachment, in the presence of deposition. This situation is termed 'source limiting' and is shown to provide a lower limit to sediment concentration. When the coverage of the deposited layer is complete so that entrainment and rainfall detachment of the original soil are considered not to occur, then the ability of the erosive agents to re-entrain and re-detach sediment in the presence of deposition limits sediment concentration. This situation, termed 'transport limiting', is shown to provide a practical upper limit to sediment concentration. This plane geometry flow model is followed by a revised model in which all processes are considered to occur but the flow of water on a plane surface is modified by the formation of rills. In this 'detailed geometry model' the spatial distribution of the erosive agents is shown to have a marked influence on the resulting processes and sediment concentrations. A potential description of the sediment transport across a change in land slope is also developed. Finally, a discussion of this new modelling approach is presented in which the conceptual developments of this thesis are considered and future developments are suggested. This discussion also includes a comparison of the outcomes of this new work with similar erosion models.
12
Wichtmann, Thorsten. "Explicit accumulation model for non-cohesive soils under cyclic loading /." Bochum : Inst. für Grundbau und Bodenmechanik, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014636041&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Buttress, Adam James. "Physicochemical behaviour of artificial lime stabilised sulfate bearing cohesive soils." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/14463/.
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Soil stabilisation is a useful civil engineering technique that enables the insitu material to be used as part of an engineered structure. Stabilised layers are used in road foundation; working platforms and for slope stabilisation and sea defences. Chemical stabilisation involves the use of a hydraulic binder (and sometimes additional pozzolans). Commonly, quicklime (CaO) or slaked-lime (Ca(OH)2) is used. On mixing into the ground, this reacts with the aluminosilicates of the clay fraction, reducing its overall water content and plasticity. Further additions increase the insitu pH. Above pH 10.4, the aluminosilicates become soluble in the pore solution. They are then able to form a range of insoluble mineral hydrates which constitute a cementitious matrix. This results in both an increase in mechanical strength and a decrease in dimensional stability. If the insitu material contains sulfur bearing mineralogies, these can react with the hydraulic binder and the aluminosilicates to form expansive minerals. If this occurs after the initial setting and hardening of the stabilised layer has occurred, it can lead to severe dimensional instability and mechanical weakening. This is termed sulfate heave and the principal agent of this heave is a hydrous calcium sulfoaluminate hydrate, ettringite (AFt). The fundamental processes of ettringite formation and associated expansion are little understood in stabilised soils. This research used a range of artificial sulfate bearing, lime stabilised blended soil samples subject to two immersion tests used for material suitability assessment in the UK. The physicochemical response (in terms of dimensional heave and mechanical weakening) was assessed as a function of soil composition and the environmental conditions imposed by the two immersion tests. The fundamental microstructure and phase composition was characterised using a range of analytical techniques (XRD, SEM-EDX, dTGA). The relationship between the observed macro-physical properties and underlying chemical environment and microstructure was explored. Key findings include that the mechanism of ettringite formation and expansion was found to be governed by the fundamental structure of the bulk clay. This explained the greater swell response of the kaolin based soils compared to those of the montmorillonite. The SEM-EDX analysis identified a primitive, Ca-rich, AFt phase termed ‘ball ettringite’, in stabilised soils. This has only relatively recently been reported in studies of cement mortars. Also, small amounts of sulfate in the bulk soil actually increase soil strength. It was suggested that the preferential formation of monosulfate (AFm) plays an important role in this mechanism. The introduction of water to the pore solution is key to the formation of ettringite. This was evidenced by X-Ray CT of the damage caused to soil specimens on immersion, as well as low angle XRD studies of the principal AFt peak. Based on the limited testing undertaken one of the immersion tests (European accelerated volumetic swell test, EN13286-49), appears to be more onerous than the other (UK CBR linear swell test, BS1924-2).
14
Marjanovic, Jana. "Stiffness characterization of mechanically-compressed cohesive soils using wave propagation." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103837.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 291-302).
Wave propagation through soils is a non-destructive method used to characterize soil stiffness properties and is the basis for geophysical interpretations. Due to the difficulty of measuring shear waves through soft cohesive soils with ultrasonic transducers, bender elements are typically used, which couple to the soft clay. Unfortunately, the stress limitation of bender elements precludes it from testing above 1.5 MPa. A novel setup using ultrasonic transducers, with electronic conditioning, is developed in order to overcome the difficulties of transmitting a shear wave through a soft material. The successful fabrication of triaxial cell endcaps fitted with ultrasonic piezoceramic elements has enabled the measurement of compressional and shear wave velocity of clays over a wide stress range (0.5 - 10 MPa). This research compares the shear modulus measurements using three different technologies that encompass a stress range of 0.1 to 70 MPa. A variety of resedimented materials and plasticities are tested in order to characterize the Vp and Vs as a function of stress during K₀-consolidation. Resedimentation creates controlled, uniform specimens whose results can develop a backbone for velocity behavior independent of field heterogeneities and disturbance. The Vp and Vs results show different trends as a function of stress for the different plasticity materials. However, the Vp/Vs ratio, which is a common indicator of unloading and lithology, has a strong dependence on the liquid limit (wL). A model is developed to predict the Vp/Vs as a function of stress for a given wL. In addition to K₀ loading, the effects of unloading are investigated. Unloading introduces secondary compression, which significantly alters the stiffness results. A method is developed to integrate the secondary compression data with normally consolidated data based on the concept of apparent preconsolidation pressure. Finally, the dynamically-obtained stiffness parameters are compared to statically-obtained constrained modulus values from static compression. By using Gassmann's fluid substitution and a corrective X factor, a new technique is developed that can predict the dynamic bulk modulus based on the static CRS measurements.
by Jana Marjanovic.
Ph. D.
15
Lee, Jangguen. "The Behavior of Pore Water Pressure in Cohesive Subgrade Soils." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1364216774.
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Hairsine, Peter Brian. "A Physically Based Model of the Erosion of Cohesive Soils." Thesis, Griffith University, 1988. http://hdl.handle.net/10072/366307.
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A new model of the erosion by water of cohesive soils is developed using physical principles. The theoretical framework which is developed recognises the changing nature of the eroding surface of a soil. Raindrop impact and overland flow are considered to act upon a soil surface so removing soil from the cohesive original (or parent) soil. Once this soil enters the overland flow, either as aggregates or primary particles, it is considered to return to the soil bed, from which it may be re-removed. The development of a deposited layer makes it necessary to distinguish between processes removing sediment from the original soil and those processes removing the deposited layer. This layer, being formed by the relatively gentle action of deposition during the current erosion event, is presumed cohesionless. The physical properties of the original soil and the deposited layer are considered to be very different. The development of two experimental apparatus, a rainfall/runoff simulator and a settling tube for the measurement of aggregate settling velocities, is first described. Experimental investigations, using these apparatus, and field observations to inform the description of the erosion and deposition processes, are then presented. The processes by which rainfall impact removes sediment from the original soil and the deposited layer are termed rainfall detachment and rainfall re-detachment respectively. Initially, descriptions of these processes in the presence of deposition, are combined in a model describing net rainfall detachment when removal of sediment from the flow bed by overland flow is not occurring. The developriient of the deposited layer is considered both quantitatively and qualitatively. The solution of the equation describing mass conservation is then given for the equilibrium situation when the mass of the deposited layer, and therefore the sediment concentration, is constant with respect to time. The processes by which overland flow removes sediment from the original soil and the deposited layer are termed entrainment and re-entrainment. The work done by the process of entrainment is considered to be done wholly against the cohesive strength of the original soil. In contrast to the process of entrainment, the work done in re-entraining sediment from the deposited layer is considered only to be done against gravity. The resulting description of these processes is then combined with the previous descriptions of rainfall detachment, rainfall re-detachment and deposition and with the equation describing the conservation of mass of sediment within any arbitary number of size (or settling velocity) classes. A plane geometry model Is developed in which the surface water flow is considered to be uniformily distributed across a plane slope on which all processes act. When the mass of the deposited layer is steady, two possible forms of equilibrium are shown to exist. When the coverage of the original soil by deposited layer is partial, the sediment concentration is limited by the removal of the cohesive original soil by entrainment and rainfall detachment, in the presence of deposition. This situation is termed 'source limiting' and is shown to provide a lower limit to sediment concentration. When the coverage of the deposited layer is complete so that entrainment and rainfall detachment of the original soil are considered not to occur, then the ability of the erosive agents to re-entrain and re-detach sediment in the presence of deposition limits sediment concentration. This situation, termed 'transport limiting', is shown to provide a practical upper limit to sediment concentration. This plane geometry flow model is followed by a revised model in which all processes are considered to occur but the flow of water on a plane surface is modified by the formation of rills. In this 'detailed geometry model' the spatial distribution of the erosive agents is shown to have a marked influence on the resulting processes and sediment concentrations. A potential description of the sediment transport across a change in land slope is also developed. Finally, a discussion of this new modelling approach is presented in which the conceptual developments of this thesis are considered and future developments are suggested. This discussion also includes a comparison of the outcomes of this new work with similar erosion models.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Division of Australian Environmental Studies
Science, Environment, Engineering and Technology
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Hers, Ian. "The analysis and interpretation of the cone pressuremeter in cohesive soils." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27884.
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The cone pressuremeter is a promising new in situ testing device which combines the well known capabilities of a piezocone with a full displacement pressuremeter (FDPM). The focus of this thesis is to present results from FDPM tests performed as part of a cone pressuremeter sounding at three cohesive soil sites in the Vancouver area.
The insertion of a cone pressuremeter results in a substantial amount of disturbance and the generation of excess pore pressures. As a result of the changing stress conditions, the length of the relaxation time or time delay between insertion and testing has a significant effect on the lift-off pressure and shape of the FDPM curve. Results indicate that increased relaxation periods lead to lower lift-off pressures. The strain rate used during a test is also significant with lower rates resulting in higher limit pressures and undrained shear strengths. Comparisons were made between the FDPM, self-boring pressuremeter (SBPM) and dilatometer lift-off and expansion pressures.
FDPM test results are also influenced by the design and performance of the pressuremeter. Important equipment related considerations discussed are compliance, strain arm design and pressuremeter L/D ratio.
The results of FDPM tests were used to estimate the undrained shear strength, shear modulus, stress history and in situ horizontal stress of cohesive soils and when possible compared to SBPM, field vane and dilatometer results.
The use of cavity expansion theory for the analysis of the FDPM test is made difficult by the unknown stress conditions created by disturbance. Nevertheless, reasonable estimates of the undrained shear strength were made using cavity expansion methods with the FDPM undrained shear strength generally greater than the field vane and similar to those obtained from the SBPM test. Cavity contraction theory was also used to estimate the undrained shear strength with the results generally being less than the field vane undrained shear strength.
Good comparisons were obtained between the FDPM and SBPM unload-reload shear moduli. Both the unload-reload shear moduli and the rigidity index were shown to attenuate with increasing shear strain.
Two new methods using the rigidity index and normalized pressuremeter limit pressure were proposed to estimate stress history. Both techniques appear to be promising. Attempts to use the FDPM to estimate the in situ horizontal stress were unsuccessful when compared to the results of other available tests.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Santagata, Maria Caterina. "Factors affecting the initial stiffness and stiffness degradation of cohesive soils." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9663.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, February 1999."December, 1998."
Includes bibliographical references.
This research investigated the pre-failure stress-strain behavior of cohesive soils through an ex.tensive testing program conducted on Resedimented Boston Blue Clay (RBBC). The uniformity and reproducibility in the behavior of this soil permitted a detailed study of the role of the following factors on both initial stiffness and small strain (Ea
Ph.D.
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Kim, Dong-Gyou. "Development of a constitutive model for resilient modulus of cohesive soils." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1078246971.
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Biswas, Sharbaree. "Study of cohesive soil-granular filter interaction incorporating critical hydraulic gradient and clogging." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060221.100311/index.html.
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Ibarra, Sandra. "A model of stress distribution and cracking in cohesive soils produced by simple tillage implements /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38205.
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The objective of this research was to further understand the behavior of the soil under the action of a tillage tool, with the purpose of finding a relation between the tool geometry and the resultant soil seed bed. Thus the problem consisted of understanding the mechanics of producing soil break up and to find a logical method of analyzing it.The problem was solved using fundamental principles of soil mechanics and force equilibrium analyzis. As a result, a mathematical model was developed which describes three failure zones within the cut soil volume. The model can be programmed into a computer to generate maps of normal and shear stresses to visualize the three failure zones.
The failure zones are the shear failure zone, the tensile fracturing zone and the no failure zone. The tensile fracturing zone is delimited by the tensile stress reaching the tensile strength of the soil at the given soil moisture content and soil density. The tensile strength of the soil was measured using an apparatus and method designed in this research.
The mathematical model gives an explanation of the mechanics of crumbling and the shape of the failed volume, but it does not give information concerning soil aggregate quality and arrangement within the soil furrow. Then, a method of analyzing the formed aggregates was developed which considers some soil physical properties of aggregates.
The study concluded that the smaller tool width and the smaller tool rake angle, among the ones used in this research, produced the most efficient geometry in producing the largest amount of soil break up, the most uniform aggregate formation and the most stable aggregate arrangement. The same tool geometry requires less energy per unit volume of soil disturbed. The best performance is produced at the lowest soil water content among those tested.
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Katti, Dinesh Ramanath. "Modelling including associated testing of cohesive soil using disturbed state concept." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185654.
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A new constitutive model for predicting the undrained stress-deformation and pore water pressure response of saturated cohesive soils subjected to cyclic loading is developed using the Disturbed State Concept (DSC) is presented in this dissertation. The model takes into account inelastic non-virgin behavior. Factors such as non-associativeness, induced anisotropy and degradation are included as disturbances with respect to two reference states. One reference state is the intact state where the material is assumed to be associative initially isotropic and hardening isotropically. It is modelled by the basic hierarchical model δ₀. The other reference state is the fully disturbed state which is assumed to be the critical state. The average response is expressed in terms of the responses corresponding to the reference states through a disturbance function D. The inelastic non-virgin loading is modelled by using interpolation functions which are made function of disturbance. Comprehensive laboratory tests have been performed on undisturbed clay samples procured from Sabine Pass, near Houston, Texas. The tests include conventional cylindrical triaxial tests and also cyclic triaxial tests in the multiaxial device with pore water pressure measurements. Some of these tests were used for determination of parameters and verification of the model. The model is verified with respect to the observed behavior of undisturbed clay samples. Verification was done with respect to laboratory tests that were used and the ones that were not used in the development of the model. The proposed model provides overall highly satisfactory predictions of the observed behavior during virgin and non-virgin loading and cyclic loading. It is concluded that the new model based on the DSC concept can correctly predict the cyclic behavior of cohesive soils and can take into account factors such as non-associativeness, induced anisotropy and degradation. The DSC concept is shown to be a powerful and general approach for constitutive modelling of geomaterials.
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Ekwue, E. I. "The influence of organic matter on the erodibility of non-cohesive soils." Thesis, Cranfield University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.331935.
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Liao, Chung-Lon. "Applications of cone, vane and vane-cone to predict stress-strain behaviour of unsaturated cohesive soil." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72788.
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Kho, Kai Tze. "An experimental study of local scour around circular bridge piers in cohesive soils." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407586.
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Marjanovic, Jana. "The study of shear and longitudinal velocity measurements of sands and cohesive soils." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74496.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 185-189).
This thesis evaluates some methods for the measurement of stiffness parameters of soils, with an emphasis on the use of bender element technology in obtaining the shear modulus. The experimental program consisted two primary stages. The beginning part of the experimentation was concerned with evaluating the behavior of bender elements, both free-standing and when applied to soil. For this case, experiments were performed on dry Ticino sand. It was concluded that the bender element tip geometry has a much greater impact than previously perceived, in particular with long, slender geometries sometimes creating directly-propagating compressional waves that interfere with the shear wave arrival detection. To reduce the uncertainty in signal interpretation, a specimen aspect ratio of 1 was adopted, with a minimum wavelength ratio of 2. The second part of the experimentation consisted of using bender elements on Boston Blue Clay, both intact samples as well as Resedimented Boston Blue Clay, created in the laboratory from processed powder. The results obtained from loading normally consolidated specimens were generally consistent and in good agreement with the literature. The unloading portion was observed to behaves differently as a function of maximum consolidation stress, with the shear modulus decreasing less during unloading as higher stress ranges are reached. In addition to the testing performed on soils, a parametric study was conducted on common materials including steel, aluminum, acrylic, and rubber in order to evaluate the results for stiffness parameters measured using extensometers, accelerometers, and ultrasonic P-wave transducers. With the conclusion of these experiments, the accelerometers were shown to have highly variable results, especially for shear wave velocity, while the other methods yielded relatively consistent, reliable results as compared to published values. Finally, a new design for a triaxial setup that enables integrated measurements of compressional and shear velocities in soil over a wide stress range is presented as groundwork for the characterization of the complete stiffness matrix of BBC.
by Jana Marjanovic.
S.M.
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Viking, Kenneth. "Vibro-driveability -a field study of vibratory driven sheet piles in non-cohesive soils." Doctoral thesis, KTH, Civil and Architectural Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3358.
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Harris, Dustin T. "Numerical model evaluations of cumulative contraction scour at a bridge site with cohesive soils." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Summer/master's/HARRIS_DUSTIN_57.pdf.
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Thesis(M.S.)--Auburn University, 2005.Abstract. Vita. "References: Curry, J.E., S.H. Crim, O. Güven, J.G. Melville, and S. Santamaria, 2003. "Scour Evaluations of Two Bridge Sites in Alabama with Cohesive Soils," Highway Research Center 930-490R, October 2003, Auburn University, AL Includes bibliographic references.
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Chang, E., E. Chang, J. Villalta, C. Fernandez, and G. Duran. "Improvement of physical, mechanical and strength behavior of cohesive soils with natural pozzolana and brick dust." Institute of Physics Publishing, 2020. http://hdl.handle.net/10757/651792.
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This research project seeks to improve soil properties through experimentation with geotechnical purposes. For this, will be used natural volcanic pozzolana in 5%, 10%, 15% and brick dust in 10% giving it a second reuse. The soil improvement will be analyzed with the proposed additions and its influence on the results. It is concluded that the addition improves the behavior of the soil by decreasing its plasticity index, increases the compaction index and improves the geotechnical parameters.
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Al-Yaseen, Muzher Alowan Hussain. "The influence of large-grained material on the initiation of scour in consolidated cohesive soils." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276864.
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Kassim, Kharul Anuar. "The geotechnical properties of lime and ash stabilised cohesive soils and their use in design." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242369.
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Zreik, Diana Alexandre 1966. "Behavior of cohesive soils and their drained, undrained, and erosional strengths at ultra-low stresses." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11725.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1995.Vita.
Includes bibliographical references (v. 2, leaves 516-532).
by Diana Alexandre Zreik.
Ph.D.
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Ghelardi, Veronica M. "Estimation of long term bridge pier scour in cohesive soils at Maryland bridges using EFA/SRICOS." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1816.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Yaman, Gokhan. "Prediction Of Geotechnical Properties Of Cohesive Soils From In-situ Tests: An Evaluation Of A Local Database." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608120/index.pdf.
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In any geotechnical design procedure, the fundemantal point to be initially clearified is the characterization of existing soil profile at a site. This requires a great deal of planning a suitable site investigation program including borings, sampling, laboratory and in situ testing etc. Laboratory and in-situ (field) tests are important tools leading to the estimation of soils properties in geotechnics. Beside laboratory tests, the measurement of engineering properties in situ is a continuously growing and developing trend, particularly in materials difficult to obtain perfect undisturbed samples.
For the purpose of this study, two large volumed geotechnical investigation reports are collected from a wide archive of 30 years experiences. Different soil types are encountered during the study like alluvial deposits of soft to stiff cohesive materials, hard clays in appearance of highly weathered rocks.
The in-situ tests mostly being focused and studied on are &ldquoPressuremeter Test&rdquo
and &ldquo
Standard Penetration Test&rdquo
on cohesive materails. Over 350 standard penetration test results are recorded together with the pressuremeter results of relevant soils. Besides, the corresponding laboratory test results of oedometer, triaxial loading and all index properties of soils are assembled. The results of in-situ tests are evaluated together with the results of laboratory tests performed on the samples obtained from related sites. The correlations between in-situ &
laboratory test results on shear strength, compressibility and deformation characteristics of soils are analysed and compared with the existing correlations in literature. The correlations are generally obtained to be in agreement with the ones in common literature in cases where the soil conditions, particularly saturation, are same in both laboratory and in-situ tests.
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Zreik, Diana Alexandre 1966. "Determination of the undrained shear strength of very soft cohesive soils by a new fall cone apparatus." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13399.
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Weidner, Katherine Lourene. "Evaluation of the Jet Test Method for determining the erosional properties of Cohesive Soils; A Numerical Approach." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/72983.
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Estimates of bank erosion typically require field measurements to determine the soil erodibility since soil characteristics are highly variable between sites, especially for cohesive soils. The submerged jet test device is an in situ method of determining the critical shear stress and soil erodibility of cohesive soils. A constant velocity jet, applied perpendicular to the soil surface, creates a scour hole which is measured at discrete time intervals. While the results of these tests are able to provide values of critical shear stress and soil erodibility, the results are often highly variable and do not consider certain aspects of scour phenomena found in cohesive soils. Jet test measurements taken on the lower Roanoke River showed that the results varied for samples from similar sites and bulk failures of large areas of soil were common on the clay banks. Computational Fluid Dynamics (CFD) can be used to determine the effect of scour hole shape changes on the applied shear stress. Previous calculation methods assumed that the depth of the scour hole was the only parameter that affected the applied shear stress. The analysis of the CFD models showed that depth did heavily influence the maximum shear stress applied to the soil boundary. However, the scour hole shape had an impact on the flow conditions near the jet centerline and within the scour hole. Wide, shallow holes yielded results that were similar to the flat plate, therefore it is recommended that field studies only use jet test results from wide, shallow holes to determine the coefficient of erodibility and the critical shear stress of cohesive soils.
Master of Science
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Serdaroglu, Mehmet Serdar. "Nonlinear analysis of pile driving and ground vibrations in saturated cohesive soils using the finite element method." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/882.
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In urban areas, vibrations generated by pile driving often affect the neighboring properties vulnerable to ground shaking. These vibrations may cause damage to surrounding structures either by shaking the ground or by causing settlement of the soil beneath foundations in the proximity of pile driving. It is important to distinguish between the conditions under which the vibrations will cause damage and those under which vibrations are tolerable. The numerical studies on the analysis of pile driving have mostly focused on assessing the driving efficiency and the bearing capacity of dynamically loaded piles. A limited number of studies included the study of ground vibrations due to pile driving and its effects on adjacent structures. However, the factors affecting the ground vibrations in soils such as the nonlinear constitutive behavior of soil, soil-pile interaction and penetration depth of the pile have not been clearly identified.
The objective of this research is to implement a numerical method to simulate dynamic loading of a single pile, and study the factors influencing the stress wave propagation in the soil surrounding the pile. The thesis is comprised of two main analyses: (1) the static analysis of a pile in which the phenomenon of static consolidation is studied, and (2) the dynamic analysis of a pile in which pile driving and ground vibrations are studied.
In the static analysis, the load capacity of a single pile is investigated. The results from the finite element method are compared with widely recognized theoretical methods. The theoretical methods that are used to estimate the end bearing capacities are: (1) General Formula, (2) Vesic's Method, (3) Janbu's Method, (4) Meyerhof's Method, and (5) Coyle & Castello's Method. The estimation of skin friction resistance (shaft capacity) of single piles is performed using the (1) Alpha method, (2) Beta method, and (3) Lambda method. Two numerical applications are performed to predict the load capacity of single piles in normally consolidated clays. It is observed that the model with no slippage at the interface predicts almost twice as much load capacity as the model with interface. In regards with the end bearing capacities, Coyle & Castello's method is found to be most conservative followed by the finite element method, the Janbu's method, the Meyerhof's method, and finally the Vesic's method. In respect to skin friction resistance, the finite element is found to be the most conservative method, followed by the Beta, the Lambda, and the Alpha method.
In the dynamic analysis, the amplitudes of ground vibrations are investigated based on the variation of: (1) the soil type, (2) the pile embedment length and (3) the released hammer energy. In the first analysis, five types of soils - loose and dense sands and, soft, medium stiff, and stiff clays - are modeled. The highest vibration amplitude is calculated for the loose sand with a peak particle velocity (PPV) of 10.0 mm/s followed by the dense sand with a PPV of around 4.0 mm/s. Among the clay types, the vibrations are higher for the stiffer clay in the near field, which is 9 m (half a pile length) or less away from the pile. In the second analysis, three different embedment lengths - full, half, and quarter pile length - are modeled. It is found that the quarter embedded piles produce greater vibration amplitudes as compared to the half and fully embedded piles. Larger amplitudes of vibrations are encountered on the ground surface for shorter pile embedment lengths. In the third analysis, three different impact forces consisting of 2,000 kN (F), 6,000 kN (3F) and 10,000 kN (5F) are applied on the pile head. It is concluded that increase in hammer energy causes increase in the peak particle velocities.
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Galli, Mario [Verfasser]. "Rheological Characterisation of Earth-Pressure-Balance (EPB) Support Medium composed of non-cohesive Soils and Foam / Mario Galli." Aachen : Shaker, 2016. http://d-nb.info/1118258533/34.
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Vieira, Juliana Matos. "Contribution of low crystalline compounds and wetting and drying cycles in the genesis of the cohesive character in Cearà soils." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10865.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorThe Coastal Plains exhibit cohesive soils, which can cause physical impediments to root penetration and water dynamics. However, in the genesis of these horizons are not completely understood. Thus, the aim of the present study was to evaluate the influence of amorphous compounds in the genesis of cohesive horizons in soils of different textures of the Coastal Plains of CearÃ, as well as verify, through physical behavior of these soils in the presence and absence of these compounds. This study also aimed to evaluate the influence of wetting and drying cycles in the density of these soils. To evaluate the effect of amorphous compounds in soil cohesion, we used samples from the air-dried cohesive horizons 9 soil profiles of the state of CearÃ, these being subjected to two treatments: with and without extraction of amorphous compounds. The samples (with and without extraction) were subjected to 3 cycles of wetting and drying, and subsequently, the penetration resistance (PR), hydraulic conductivity and bulk density were determined. To assess the influence of wetting and drying cycles in the density of these soils were performed 3 different levels of wetting and drying cycles (3, 6, 9 cycles). After these cycles, penetration resistance resistance and density were evaluated. The additions of silica and aluminum low crystalline (amorphous) in cohesive soils show that these compounds contribute jointly in the genesis of these horizons. Regardless of texture, soil that passed through the extraction process of amorphous compounds showed a significant reduction in soil resistance to penetration and density. It was found that these soils, the hydraulic conductivity was higher than that observed in soil without extraction of amorphous compounds. Thus, it is clear the contribution of these compounds in the hardening in cohesive soils. With regard to the effects of wetting and drying cycles assessed characteristics of the soil (RP and density), it was observed that in general, increasing the number of cycles caused a subtle increase in bulk density. Soils that have gone by 9 cycles of wetting and drying showed a remarkable increase in RP in relation to soils soils that have undergone 3and 6 cycles.
Os Tabuleiros Costeiros apresentam solos com carÃter coeso, os quais podem ocasionar impedimento fÃsico à penetraÃÃo das raÃzes e à dinÃmica da Ãgua. No entanto, a gÃnese desses horizontes nÃo està completamente esclarecida. Dessa forma, objetivou-se com o presente trabalho avaliar a influÃncia de compostos amorfos na gÃnese de horizontes com carÃter coeso em solos de diferentes texturas dos Tabuleiros Costeiros do CearÃ, bem como verificar, atravÃs de anÃlises fÃsicas o comportamento desses solos na presenÃa e na ausÃncia desses compostos. Objetivou-se tambÃm, avaliar a influÃncia de ciclos de umedecimento e secagem no adensamento desses solos. Para avaliaÃÃo do efeito dos compostos amorfos na coesÃo dos solos, foram utilizadas amostras de TFSA de horizontes com carÃter coeso de 9 perfis de solo do estado do CearÃ, sendo estas, submetidas a 2 tratamentos: com e sem extraÃÃo de compostos amorfos. As amostras (com e sem extraÃÃo) foram submetidas a 3 ciclos de umedecimento e secagem e, posteriormente, a resistÃncia à penetraÃÃo (RP), condutividade hidrÃulica e densidade do solo foram determinadas. Para avaliaÃÃo da influÃncia dos ciclos de umedecimento e secagem no adensamento desses solos, foram aplicados 3 diferentes nÃmeros de ciclos de umedecimento e secagem (3, 6, 9 ciclos). ApÃs esses ciclos, a resistÃncia do solo à penetraÃÃo e densidade foram avaliadas. Os acrÃscimos de sÃlica e de alumÃnio de baixa cristalinidade (amorfos) nos horizontes coesos evidenciam que esses compostos contribuem conjuntamente na gÃnese destes horizontes. Independente da textura, os solos que passaram pelo processo de extraÃÃo de compostos amorfos apresentaram uma reduÃÃo significativa na resistÃncia do solo à penetraÃÃo e na densidade. Verificou-se que nesses solos, a condutividade hidrÃulica foi superior Ãquela observada nos solos sem a extraÃÃo dos compostos amorfos. Desse modo, fica clara a contribuiÃÃo desses compostos no endurecimento dos solos coesos. No que se refere aos efeitos dos ciclos de umedecimento e secagem nas caracterÃsticas avaliadas do solo (RP e densidade), observou-se que de um modo geral, o aumento do nÃmero de ciclos provocou um sutil aumento na densidade do solo. Os solos que passaram pelos 9 ciclos de umedecimento e secagem apresentaram um aumento significativo na RP em relaÃÃo aos solos que solos que passaram por 3 e 6 ciclos.
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Terceros, Almanza Mauricio Marcelo [Verfasser]. "A new p-y approach to pile foundations with arbitrary dimensions under monotonic load in cohesive soils / Mauricio Marcelo Terceros Almanza." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://nbn-resolving.de/urn:nbn:de:101:1-2021093002162796802790.
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Galli, Mario [Verfasser], Markus [Gutachter] Thewes, and Daniele [Gutachter] Peila. "Rheological characterisation of earth-pressure-balance (EPB) support medium composed of non-cohesive soils and foam / Mario Galli ; Gutachter: Markus Thewes, Daniele Peila." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1114497002/34.
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Lira, Rodolfho de Aquino. "Efeito do Uso sobre a Coesão de Solo Cultivado com Cana- de- Açúcar em Tabuleiro Costeiro de Pernambuco." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16623.
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FACEPE
Os tabuleiros costeiros ocupam uma extensa área no litoral brasileiro e devido a seu relevo plano favorável à mecanização, precipitação pluvial alta e proximidade com os grandes centros consumidores, são as áreas de uso agrícola mais intensificado. Os solos predominantes nessa área são em geral, profundos, de baixa fertilidade natural e muitas vezes ocorrem com uma camada adensada, configurando os solos coesos. Esta coesão tem afetado propriedades físicas, químicas e hídricas do solo, que interferem diretamente no estabelecimento do cultivo e, consequentemente, na produtividade das culturas e renda dos agricultores. Os agricultores, em situações como esta, muitas vezes tendem a desmatarem mais áreas para cultivo, visando compensar perdas econômicas, causando impactos ambientais. O objetivo deste estudo foi avaliar o efeito do uso, sobre a resistência no horizonte coeso, em solos sob manejo de cana-de-açúcar e mata nativa, na unidade geoambiental dos Tabuleiros Costeiros de Pernambuco, a partir de ensaios físico-hídricos. Foram abertos um perfil em área de plantio de cana-de-açúcar e um em mata nativa, e coletadas amostras estruturadas do horizonte coeso. Os atributos físicos avaliados foram: Porosidade Total (macro, meso, micro e criptoporosidade), densidade do solo (Ds), curva característica de retenção de água no solo (CCRAS) e resistência do solo à penetração de raízes (RP). As médias dos parâmetros físicos analisados foram submetidas à análise de variância (ANOVA) e para os parâmetros que apresentam diferenças significativas foi aplicado o teste de Tukey, por meio do aplicativo SAS. A resistência à penetração foi um atributo eficiente para avaliar coesão dos solos estudados. Os manejos distintos não apresentaram diferença significativa nos valores de densidade Ds. A área cultivada apresentou maior capacidade de retenção de água, avaliada pelas curvas características de retenção, evidenciando que o manejo influenciou no tamanho dos poros. Na área de mata poderá ocorrer maior secamento do solo, sem que haja valores restritivos de resistência à penetração, pois precisará de um menor valor de umidade para que não haja impedimentos ao desenvolvimento do sistema radicular.
The costal plains occupates an extensive area in brazilian’s litoral and due to its plain relief suitable to mechanization, high pluvial precipitation and proximity with the big consumer centers, are intensified agricultural areas. The predominant soils in this area are in general, deep, of low natural fertility and most of the times occur with a condensed layer, setting the cohesive soils. This cohesion has affected physical, chemical and hydrous properties of the soil, which interfere directly in the settlement of the cultivation and, consequently, in the crops productivity and income of the farmers. The farmers, in situations like this, many times tend to deforest more areas to cultivation, aiming to compensate economic losses, causing environmental damage. The goal of this study was to evaluate the effect of the use in the resistance of the cohesive horizon, on soils under management of sugar cane and native forest in the geo environmental unit of the coastal plains of Pernambuco, from hydrous physical tests. It was opened a profile in the sugarcane area and another native forest, structured and collected samples of cohesive horizon. The assessed physical attributes were: Total porosity (macro, meso, micro and criptoporosidade), bulk density (Ds), water retention curve characteristic in the soil (CCRAS) and soil resistance to root penetration (RP). The average of the physical parameters analyzed were subjected to analysis of variance (ANOVA) and to the parameters that show significant differences was used the Tukey test, using the SAS software. The penetration resistance was an effective attribute to evaluate the cohesion of soils studied. The different managements showed no significant difference in density values Ds. The crapped area presented higher water holding capacity, when evaluated by retention curves, showing that the management influenced the pore size. In forest area may occur more soil drying, without restrictive values of penetration resistance because need a lower moisture value so there are no impediments to the development of the root system.
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Hazell, Edmund. "Numerical and experimental studies of shallow cone penetration in clay." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:6b5380f1-2d02-4da0-92e0-ae83ad5c4698.
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The fall-cone test is widely used in geotechnical practice to obtain rapid estimates of the undrained shear strength of cohesive soil, and as an index test to determine the liquid limit. This thesis is concerned with numerical modelling of the penetration of solids by conical indenters, and with interpretation of the numerical results in the context of the fall-cone test. Experimental studies of shallow cone penetration in clay are also reported, with the aim of verifying the numerical predictions. The practical significance of the results, in terms of the interpretation of fall-cone test results, is assessed. Results are reported from finite element analyses with the commercial codes ELFEN and Abaqus, in which an explicit dynamic approach was adopted for analysis of continuous cone indentation. Quasi-static analyses using an elastoplastic Tresca material model are used to obtain bearing capacity factors for shallow cone penetration, taking account of the material displaced, for various cone apex angles and adhesion factors. Further analyses are reported in which a simple extension of the Tresca material model, implemented as a user-defined material subroutine for Abaqus, is used to simulate viscous rate effects (known to be important in cohesive soils). Some analyses with the rate-dependent model are displacement-controlled, while others model the effect of rate-dependence on the dynamics of freefall cone indentation tests. Laboratory measurements of the forces required to indent clay samples in the laboratory are reported. Results from displacement-controlled tests with imposed step-changes in cone speed, and from freefall tests, confirm that the numerical rate-dependent strength model represents the observed behaviour well. Some results from experiments to observe plastic flow around conical indenters are also presented. Finally, additional numerical analyses are presented in which a critical state model of clay plasticity is used to study the variation of effective stress, strain and pore pressure around cones in indentation tests at various speeds.
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Zuffo, Valmir José. "Efeitos de diferentes preparos nos atributos físicos do solo e no desempenho produtivo do mamoeiro Tainung 01." Universidade Federal do Espírito Santo, 2012. http://repositorio.ufes.br/handle/10/5590.
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Previous issue date: 2012-04-25Avaliaram-se os efeitos de cinco sistemas de preparo do solo nos atributos físicos de um Argissolo Amarelo coeso de Tabuleiro, bem como no crescimento, desenvolvimento e nutrição do mamoeiro Formosa Tainung 01 irrigado. O experimento foi instalado em 21/01/2011 e conduzido a campo por 260 dias, em área anteriormente utilizada com pastagem de Brachiaria nunca corrigida ou fertilizada, irrigada por sistema de aspersão de baixa pressão. Os tratamentos, implantados em cinco repetições e em delineamento de blocos ao acaso foram: 1) grade aradora (duas vezes) + niveladora + camalhão sobre a linha confeccionado 135 após transplantio (GA c/ CAM); 2) grade aradora (duas vezes) + niveladora (GA s/ CAM); 3) subsolador florestal (SF); 4) grade aradora (duas vezes) + niveladora + escarificação com 3 hastes sobre a linha de plantio (GA + ELP); 5) grade aradora (duas vezes) + niveladora + escarificação com 3 hastes em área total (GA + EAT). Os preparos receberam sulcamento mecanizado e banquetas, confeccionadas manualmente com terra solta do sulco, que foram niveladas e fertilizadas para receber as mudas. Antes da implantação dos tratamentos a área experimental foi caracterizada quanto à resistência mecânica à penetração (RP) acompanhada pela umidade do solo, diâmetro médio ponderado (DMP), diâmetro médio geométrico (DMG), densidade do solo (Ds), macroporosidade (Ma), microporosidade (Mi), relação Ma/Mi, textura do solo e fertilidade. Após a implantação dos tratamentos foram determinadas RP, acompanhada pela umidade do solo, DMP, DMG, Ds, Ma, Mi, relação Ma/Mi e variáveis biométricas de nutrição e produção como altura de plantas, diâmetro do tronco a 0,20 m de altura, altura de inserção do primeiro fruto, sexo das plantas, teores foliares de macro e micronutrientes bem como número de frutos por planta com separação de frutos comerciais e não comerciais. O tratamento estatístico dos dados constou de cálculo do erro padrão da média para os dados de RP e para os demais dados, análise de variância e teste de Tukey a nível de 5% de probabilidade. Houve diferenças de resistência à penetração entre os tratamentos. O subsolador mostrou-se mais efetivo na diminuição da RP até 0,35 m de distância da planta no sentido transversal à linha de plantio. O escarificador resultou em menores RP do que GA ou SF, mesmo a 0,40 m de profundidade, e foi mais eficiente a maiores distâncias transversalmente à planta. Todos os preparos provocaram RP menores do que 2,5 MPa na profundidade de maior concentração de raízes do mamoeiro (0 0,25 m) fornecendo boas condições físicas até essa profundidade. Não houve diferença estatística entre os tratamentos para Ds, Ma, Mi, relação Ma/Mi, DMP e DMG a 0,20 m de profundidade e teores foliares de macro e micronutrientes aos 197 dias após transplantio. A altura de plantas em duas épocas foi menor para o SF e igual estatisticamente para os outros tratamentos. A grade aradora alterou os atributos físicos do solo em maior intensidade até 0,20 m de profundidade. A produção total de frutos e de frutos comerciais foi maior nos preparos GA c/ CAM, GA s/ CAM, GA+ELP e GA+EAT, os quais não diferiram entre si. Não houve diferenças para produtividade de frutos não comerciais. Não se justificou o uso do camalhão sobre a linha de plantio confeccionado após o transplantio. Do ponto de vista de conservação do solo, quando considerados os dados de estabilidade de agregados, os preparos foram semelhantes. A relação entre o crescimento e desenvolvimento das plantas e diferentes preparos de solo deve ser avaliada considerando o conjunto de atributos físicos e químicos do solo
The effects of five tillage systems on soil physical attributes, growth, development and nutrition of Formosa papaya Tainung 01 were evaluated on cohesive Alfisol of Coastal Tableland. The experiment was planted on january 21, 2011 and remained in field for 260 days, in an area previously used with Brachiaria never corrected nor fertilized before and irrigated by low pressure sprinkler system. Treatments were applied in five replicates and statistical design of random blocks were: 1) heavy disc harrow (twice) + offset disc harrow + ridge on row planting made 135 days after transplanting (GA c/ CAM); 2) heavy disc harrow (twice) + offset disc harrow (GA s/ CAM); 3) forester subsoiler (SF); 4) heavy disc harrow (twice) + offset disc harrow + chisel plow on row planting (GA+ELP); 5) heavy disc harrow (twice) + offset disc harrow + chisel plow on total area (GA+EAT). All tillage systems received mechanized furrower and a bench made with loose soil and fertilizers and over which the seedlings were planted. As a characterization of experimental area before application of treatments, were determined penetration resistance (RP) followed by soil moisture, mean weight diameter (DMP), geometric mean diameter (DMG), bulk density (Ds), macroporosity (Ma), microporosity (Mi), Ma/Mi ratio, soil texture and fertility. After application of treatments were determined RP, accompanied by soil moisture, DMP, DMG, Ds, Ma, Mi and Ma/Mi ratio and biometric variables of nutrition and production as plant height, stem diameter at 0,20 m height, height of insertion of the first fruit, plant sex, foliar contents of macro and micronutrients as well as number of fruits per plant with separation of commercial and non-commercial ones. Statistical treatment of data included calculation of mean standard error for RP and analysis of variance for all other data accompanied by the Tukey test for comparison of means at 5% level of probability. There were differences in penetration resistance between treatments. Subsoiler showed to be more effective in the decrease of RP up to 0,35 m away from the plant in the direction transverse to the rows. Chisel plow produced smaller RP than GA or SF, even at 0,40 m depth and was more effective at greater distances from the plant. All tillage systems produced RP smaller than 2.5 MPa at a depth with the greater concentration of papaya roots (0 0.25 m) and provided good physical conditions up to this depth. There was no statistical difference between treatments for Ds, Ma, Mi, Ma/Mi ratio, DMP e DMG at 0.20 m depth and foliar contents of macro and micronutrients at 197 days after transplanting. Height of plants in two stages were lower for the SF and statistically equal to the other treatments. Heavy disc harrow altered soil physical attributes at a higher intensity up to 0.20 m depht. Total fruit yield and commercial fruit yield was higher in GA c/ CAM, GA s/ CAM, GA+ELP and GA+EAT, which did not differ. There were no differences for non-commercial fruit yield. There was no justification for the building of the ridge on the planting row after instalation of the orchard. From the standpoint of conservation of soil, when considering the stability of aggregates data, all tillage systems were similar. The relationship between growth and development performance of plants and tillage systems should be evaluated considering whole physical and chemical properties of soil
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VASCONCELOS, Romero Falcão Bezerra de. "Comportamento mecânico de um Latossolo Amarelo Distrocoeso não saturado sob diferentes sistemas de manejo culturais da cana-de-açúca." Universidade Federal Rural de Pernambuco, 2009. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5378.
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The soils of the Coastal Plains cultivated with sugarcane for a long period of time under different management systems may make changes in physical and chemical properties and the state of soil aggregation. Considering the above, the objective of this study was to evaluate the effects of different management systems with sugarcane on the chemical and physical properties of a dystrophic cohesive Yellow Latosol of coastal tablelands of Alagoas. Plots were selected in areas of production in the growing of sugarcane, and the object of experimental research three areas, representative of three management systems adopted by sugarcane production unit, namely: a cultivated area under irrigation management system (SMI), an area under the management system of fertirrigation with vinasse (SMV) and area under a management system with application of vinasse + filter tart (SMVT). These management systems were compared and on the witness pattern represented by native forest (NF). To assess the physical and chemical properties and aggregation state of the soil, the soil samples were collected at random in the areas subject to different management systems, in the depths of 0- 0,20; 0,20-0,40 and 0,40-0,60 m, being withdrawn at a point between the lines of sugarcane. The results were submitted to analysis of variance and the averages compared by Tukey test to 5% significance. Study of simple correlations were performed between some variables measures. The results showed that the different management systems promoted investigated changes in physical and chemical properties and the state of soil aggregation. The parameters of consistency of the soil tended to increase the humidity in their values with the increase of total organic carbon (TOC) of soil, promoted by the addition of waste from sugar cane. The studies of simple correlations between the total organic carbon (TOC) and the rates of stability of aggregate investigated, showed significant (p<0,01) correlation and positive. The management systems that received the addition of waste from sugarcane showed less deterioration in physical and chemical properties of soil in the soil under native forest (NF).
Os solos dos tabuleiros costeiros cultivados com cana-de-açúcar, durante longo período de tempo, sob diferentes sistemas de manejo, podem apresentar alterações nas propriedades físicas e químicas e no estado de agregação. O objetivo do trabalho foi avaliar os efeitos de diferentes sistemas de manejo com cana-de-açúcar sobre as propriedades físicas e químicas de um Latossolo Amarelo Distrocoeso dos tabuleiros costeiros de Alagoas. Foram selecionadas áreas em talhões de produção com a cultura da cana-de-açucar, sendo objeto de pesquisa experimental três áreas, representativas de três sistemas de manejo adotados pela unidade sucroalcooleira, a saber: uma área cultivada sob sistema de manejo irrigado (SMI), uma área sob sistema de manejo de fertirrigação com vinhaça (SMV) e uma área sob sistema de manejo com aplicação de vinhaça + torta de filtro (SMVT). Esses sistemas de manejo foram comparados entre si e em relação a uma testemunha padrão, representada por uma mata nativa (MN). Para avaliar as propriedades físicas e químicas e o estado de agregação do solo, amostras de solo foram coletadas ao acaso, nas áreas submetidas aos diferentes sistemas de manejo, nas profundidades de 0-0,20; 0,20-0,40 e 0,40-0,60 metros, sendo retiradas num ponto situado nas entrelinhas da cana-de-açúcar. Os resultados obtidos foram submetidos a análise de variância e as médias comparadas pelo teste de Tukey, a 5% de significância. Estudos de correlações simples foram realizados entre algumas variáveis medidas. Os resultados permitiram concluir que os diferentes sistemas de manejo investigados promoveram alterações nas propriedades físicas e químicas e no estado de agregação do solo. Os parâmetros de consistência do solo apresentaram tendência de aumento em seus valores de umidade com o incremento do carbono orgânico total (COT) do solo, promovido pela adição de resíduos da cana-de-açúcar. Os estudos de correlações simples entre o carbono orgânico total (COT) e os índices de estabilidade de agregados investigados apresentaram correlações significativas (p<0,01) e positivas. Os sistemas de manejo que receberam adição de resíduos da cana-de-açúcar denotaram menor degradação nas propriedades físicas e químicas do solo, em relação ao solo sob mata nativa (MN).
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Santos, Joildes Brasil. "Parâmetros físico-ambientais para compartimentação geoambiental e delimitação da ocorrência de solos coesos na depressão do São Francisco, BA." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4645.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Studies on cohesive soils in Brazil and worldwide indicate that cohesion in the soil is a factor of natural limitation to agricultural use. However, in the region of the Coastal Tablelands in Northeast Brazil these soils are used through use and management techniques adapted to their natural limitations, such as high resistance to penetration, hard when dry and friable when moist, with high density and reduced effective depth, depending of dense horizon. As for the cohesion process in the soil, would be related to the accumulation clay soil filling the pores and increase its density, making them more resistant to penetration of roots. The silicification process could also be related to the formation of cohesive horizon because that silica is one of the principal cementing agents in this process in various regions of the planet. In addition, climate alternating between dry season and wet season this would also enhance soil compaction. In this study we discuss the presence of soils with cohesive horizon in Oxisols and Ultisols Yellow Yellows geomorphological unit called Depression of the San Francisco-BA, focusing on the area of the snail farm that featured a soil survey in detail. From a geo-environmental partitioning was presented a summary with the main features of the landscape, in order to understand the environment in which this type of soil occurs. And with the help of physical and environmental parameters of the relief (hipsometria, slope and curvature of the sides), use and vegetation and soil properties (isovalue of clay and silica content), it was possible to create a map with the location of the area with potential occurrence of cohesive soils for Farm Caracol, which certainly extends outside its boundaries.
Estudos sobre solos coesos no Brasil e no mundo apontam que a coesão no solo é um fator de limitação natural à utilização agrícola. Entretanto, na região dos Tabuleiros Costeiros no Nordeste Brasileiro esses solos são utilizados mediante técnicas de uso e manejo adaptados às suas limitações naturais, como alta resistência a penetração, duro quando secos e friáveis quando umedecidos, com alta densidade e profundidade efetiva diminuída, em função de horizonte adensado. Quanto ao processo de coesão no solo, estaria relacionado ao acúmulo de argila preenchendo os poros do solo e aumentando sua densidade, tornando-os mais resistentes à penetração de raízes. O processo de silicificação também poderia ser relacionado à formação do horizonte coeso, pois que a sílica é um dos principais agentes cimentantes nesse processo em várias regiões do planeta. Em adição, a alternância climática entre estação seca e estação úmida também intensificaria esse adensamento do solo. Nesta pesquisa é discutida a presença de solos com horizonte coeso em Latossolos Amarelos e Argissolos Amarelos da Unidade Geomorfológica denominada Depressão do São Francisco-BA, com foco na área da Fazenda Caracol que contou com um levantamento de solos em detalhe. A partir de uma compartimentação geoambiental foi apresentada uma síntese com as principais características físicas da paisagem, com o objetivo de entender o ambiente em que esse tipo de solo ocorre. E com auxílio de parâmetros físico-ambientais do relevo (hipsometria, declividade e curvatura das vertentes), do uso e vegetação e alguns atributos do solo (isovalores dos teores de argila e sílica), foi possível criar um mapa com a localização da área com potencial de ocorrência dos solos coesos para a Fazenda Caracol, a qual certamente se prolonga para fora de seus limites.
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Muller, Eugene 1951. "In situ measurement of the cohesion of a cemented alluvial soil." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277090.
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A modified plate load (MPL) test was developed to measure the in situ cohesion of a carbonate or caliche cemented soil. The MPL test was performed on the crest of a vertical cut in alluvial soil with a steel plate loaded until the soil failed. A three-dimensional slope stability analysis was then used to back calculate soil cohesion. In situ test results were used in conjunction with laboratory testing of deaggregated soils samples to completely define the Mohr-Coulomb strength parameters of the in situ soil. In order to check the result of the in situ test procedure, the field test conditions were modeled for use in a two-dimensional slope stability analysis using the computer program CSLIP1. A comparison of the results shows reasonable values of soil cohesion were obtained using the MPL test method.
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Parks, Olivia Waverly. "Effect of water temperature on cohesive soil erosion." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49663.
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In light of increased stream temperatures due to urbanization and climate change, theeffect of water temperature on cohesive soil erosion should be explored. The objectives of this study are to: determine the effect of water temperature on the erosion rates of clay; determine how erosion rates vary with clay mineralogy; and, explore the relationship between zeta potential and erosion rate. Samples of kaolinite- and montmorillonite-sand mixtures, and vermiculite-dominated soil were placed in the wall of a recirculating flume channel using a vertical sample orientation. Erosion rate was measured under a range of shear stresses (0.1-20 Pa) for a period of five minutes per shear stress at water temperatures of 12, 20, and 27�"C. The zeta potential was determined for each clay type at the three testing temperatures and compared to mean erosion rates. The kaolinite erosion rate doubled when the temperature increased from 12 to 20�"C, and erosion of vermiculite samples tripled when the temperature increased from 20 to 27�"C. The montmorillonite samples generally eroded through mechanical failure rather than fluvial erosion, and the limited fluvial erosion of the montmorillonite-sand mixture was not correlated with water temperature. The data suggest correlation between zeta potential and erosion rate; however, due to the small sample size (n=3), statistically significant correlation was not indicated. Research should continue to explore the influence of water temperature on cohesive soil erosion to better understand the influence of clay mineralogy. Due to the high degree of variability in cohesive soil erosion, multiple replications should be used in future work. The vertical sample orientation enabled discrimination between fluvial erosion and mass wasting and is recommended for future studies.
Master of Science
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Khasawneh, Mohammad Ali. "LABORATORY CHARACTERIZATION OF COHESIVE SUBGRADE MATERIALS." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1124387175.
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Ingram, Ronald J. "Geosynthetic-soil interface properties for cohesionless and cohesive media." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4813.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xv, 150 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 137-140).