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Baleshwar Singh - One of the best experts on this subject based on the ideXlab platform.
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Shear Strength and Deformation Behaviour of Glass Fibre-Reinforced Cohesive Soil with Varying Dry Unit Weight
2019Co-Authors: Suchit Kumar Patel, Baleshwar SinghAbstract:Proctor compaction and consolidated undrained triaxial tests were carried out to investigate the effects of glass fibre reinforcement on the shear strength and deformation behaviour of a Cohesive Soil under different compaction states. The fibre diameter was 0.15 mm, varying in length from 10 to 30 mm, and in content from 0 to 4% by weight of the dry Soil. The separate and joint effects of fibre content, fibre length, confining pressure and dry unit weight on the deviator stress response, pore water pressure response, deformation mode, stiffness and shear strength of the specimens were evaluated. The shear strength of the reinforced Soil increases with the moulding dry unit weight, though the optimum fibre content and fibre length remain the same for all dry unit weights. Multiple-regression statistical analysis was carried out to develop an expression for predicting the major principal stress at failure of the glass fibre-reinforced Cohesive Soil.
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Experimental Investigation on the Behaviour of Glass Fibre-Reinforced Cohesive Soil for Application as Pavement Subgrade Material
2017Co-Authors: Suchit Kumar Patel, Baleshwar SinghAbstract:Proctor compaction and California bearing ratio (CBR) tests were performed on glass fibre-reinforced Cohesive Soil to investigate its suitability as a subgrade material. The effects of varying fibre content, fibre length, compacted moisture content and soaking period on CBR and secant modulus were investigated. The test results indicate marginal variation of MDU and OMC with glass fibre reinforcement. Unsoaked CBR test was conducted on specimens compacted at optimum moisture content (OMC) and at 2% wet and dry sides of OMC, whereas soaked CBR test was conducted only on specimens compacted at OMC. CBR value increases with penetration depth up to 5.08 and 7.62 mm under unsoaked and soaked conditions, respectively. Both CBR and secant modulus increase with fiber content and fiber length at any compacted state. They decrease on either side of OMC, and also with increasing soaking period. The reinforcement benefit increases with increasing fiber content up to 0.75% for any fiber length and testing condition. The maximum enhancement in CBR are 2.77 and 2.85 times with 0.75% fibre reinforcement of 20 mm length, under unsoaked and soaked conditions, respectively. Using the glass fibre-reinforced Soil in the subgrade may cause reduction of pavement thickness up to 25% even for a traffic value of 150 msa.
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strength and deformation behavior of fiber reinforced Cohesive Soil under varying moisture and compaction states
2017Co-Authors: Suchit Kumar Patel, Baleshwar SinghAbstract:An experimental study was carried out to investigate the effects of glass fiber reinforcement on the strength and deformation behavior of a Cohesive Soil under different compaction states by means of unconfined compression tests. The specimens were prepared with varying fiber contents, fiber lengths, dry unit weight and moisture content other than maximum dry unit weight and optimum moisture content of the Soil. From the test results, peak strength, failure axial strain, secant modulus and energy absorption capacity of the reinforced Soil specimens were calculated and compared with that of the unreinforced Soil. The results showed that the relative benefits of fiber reinforcement are highly dependent on the moisture content and dry unit weight of the Soil specimens. The peak strength of the reinforced Soil specimen increases gradually with increase in dry unit weight, whereas the improvement of peak strength with moisture content occurs up to optimum moisture content. The brittle failure pattern with a single distinct shear plane of the unreinforced Soil specimens is gradually transformed to multi-shear failure pattern along with barreling shape at low fiber content, and then to plastic bulging failure with a network of minor fissures at higher fiber content.
Baojian Zhang - One of the best experts on this subject based on the ideXlab platform.
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geogrid reinforced lime treated Cohesive Soil retaining wall case study and implications
2012Co-Authors: Guangqing Yang, Huabei Liu, Baojian ZhangAbstract:Abstract Lime-treated Cohesive Soils are used extensively as the construction materials of road embankments. In some cases, vertical embankment is needed, rendering the necessity to employ retaining walls backfilled with lime-treated Cohesive Soil. In China, geogrid-reinforced lime-treated Cohesive Soil retaining walls are increasingly used for this purpose. With the objective to reveal the behavior of this type of structure under working-stress condition and to shed light on its future application, a 6.0 m reinforced Soil retaining wall was monitored for two years during and post construction. The results showed that the lime-treated Soil carried the majority of the gravity load but the geogrid reinforcements also contributed to the integrity of the embankment. Under gravity loading, the backfill deformation was mainly elastic. Backfill compaction during construction was the critical factor influencing the reinforcement deformation and lateral earth pressure at the back of the facing, the latter of which decreased with time after the end of construction due to the increases of both backfill strength and facing displacement. Based on these results, it is inferred that under working stress condition, lime-treated backfill plays a major role in the stability of the retaining wall, while geogrid reinforcements play a secondary role.
Erdin Ibraim - One of the best experts on this subject based on the ideXlab platform.
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modelling of fibre Cohesive Soil mixtures
2014Co-Authors: Andrea Diambra, Erdin IbraimAbstract:A new constitutive model for fibre-reinforced Cohesive Soil is proposed. The model combines a Cam-Clay like bounding surface model with an elastic–plastic one-dimensional fibrous element model. A “smearing procedure”, which can consider any spatial distribution of fibre orientation, is employed to transform discrete tensile forces developed in the fibres into stresses for the composite material. The fibre stress contribution is bounded by both degradation of Soil–fibre bonding due to pull-out mechanism and tensile strength of the fibres. Eventual occurrence of fibre breakage is also considered. The model performances are analysed for both consolidation and shearing loading modes, and qualitative comparison is performed with experimental data available in the literature. For consolidation loading, tensile stresses are not developed in the fibres and thus the fibre effect is rather limited. For drained shear loading, addition of fibres can result in a consistent shear strength increase. The beneficial effect of fibres seems to be controlled by two parameters: the fibre tensile stiffness and the fibre/Soil strain ratio that accounts for any possible slippage or shear deformation at the fibre/Soil matrix interface. For undrained shear loading, the strengthening effect of the fibres appears to be counteracted by the increase in pore water pressure, induced by the additional confining contribution of the fibres. In agreement with published experimental data, the model suggests also that the moisture content is a key factor governing fibre effectiveness for undrained shearing. Finally, analysis of the model predicted critical states for fibre-reinforced Cohesive Soil is provided.
Suchit Kumar Patel - One of the best experts on this subject based on the ideXlab platform.
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Shear Strength and Deformation Behaviour of Glass Fibre-Reinforced Cohesive Soil with Varying Dry Unit Weight
2019Co-Authors: Suchit Kumar Patel, Baleshwar SinghAbstract:Proctor compaction and consolidated undrained triaxial tests were carried out to investigate the effects of glass fibre reinforcement on the shear strength and deformation behaviour of a Cohesive Soil under different compaction states. The fibre diameter was 0.15 mm, varying in length from 10 to 30 mm, and in content from 0 to 4% by weight of the dry Soil. The separate and joint effects of fibre content, fibre length, confining pressure and dry unit weight on the deviator stress response, pore water pressure response, deformation mode, stiffness and shear strength of the specimens were evaluated. The shear strength of the reinforced Soil increases with the moulding dry unit weight, though the optimum fibre content and fibre length remain the same for all dry unit weights. Multiple-regression statistical analysis was carried out to develop an expression for predicting the major principal stress at failure of the glass fibre-reinforced Cohesive Soil.
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Experimental Investigation on the Behaviour of Glass Fibre-Reinforced Cohesive Soil for Application as Pavement Subgrade Material
2017Co-Authors: Suchit Kumar Patel, Baleshwar SinghAbstract:Proctor compaction and California bearing ratio (CBR) tests were performed on glass fibre-reinforced Cohesive Soil to investigate its suitability as a subgrade material. The effects of varying fibre content, fibre length, compacted moisture content and soaking period on CBR and secant modulus were investigated. The test results indicate marginal variation of MDU and OMC with glass fibre reinforcement. Unsoaked CBR test was conducted on specimens compacted at optimum moisture content (OMC) and at 2% wet and dry sides of OMC, whereas soaked CBR test was conducted only on specimens compacted at OMC. CBR value increases with penetration depth up to 5.08 and 7.62 mm under unsoaked and soaked conditions, respectively. Both CBR and secant modulus increase with fiber content and fiber length at any compacted state. They decrease on either side of OMC, and also with increasing soaking period. The reinforcement benefit increases with increasing fiber content up to 0.75% for any fiber length and testing condition. The maximum enhancement in CBR are 2.77 and 2.85 times with 0.75% fibre reinforcement of 20 mm length, under unsoaked and soaked conditions, respectively. Using the glass fibre-reinforced Soil in the subgrade may cause reduction of pavement thickness up to 25% even for a traffic value of 150 msa.
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strength and deformation behavior of fiber reinforced Cohesive Soil under varying moisture and compaction states
2017Co-Authors: Suchit Kumar Patel, Baleshwar SinghAbstract:An experimental study was carried out to investigate the effects of glass fiber reinforcement on the strength and deformation behavior of a Cohesive Soil under different compaction states by means of unconfined compression tests. The specimens were prepared with varying fiber contents, fiber lengths, dry unit weight and moisture content other than maximum dry unit weight and optimum moisture content of the Soil. From the test results, peak strength, failure axial strain, secant modulus and energy absorption capacity of the reinforced Soil specimens were calculated and compared with that of the unreinforced Soil. The results showed that the relative benefits of fiber reinforcement are highly dependent on the moisture content and dry unit weight of the Soil specimens. The peak strength of the reinforced Soil specimen increases gradually with increase in dry unit weight, whereas the improvement of peak strength with moisture content occurs up to optimum moisture content. The brittle failure pattern with a single distinct shear plane of the unreinforced Soil specimens is gradually transformed to multi-shear failure pattern along with barreling shape at low fiber content, and then to plastic bulging failure with a network of minor fissures at higher fiber content.
Ga Zhang - One of the best experts on this subject based on the ideXlab platform.
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centrifuge model test study on pile reinforcement behavior of Cohesive Soil slopes under earthquake conditions
2014Co-Authors: Liping P Wang, Ga ZhangAbstract:In this study, dynamic centrifuge model tests were conducted to investigate the dynamic response of Cohesive Soil slopes with the use of stabilizing piles during an earthquake. The behavior of the pile reinforcement was analyzed based on the obtained deformation over the entire slope through image-based measurement, and the behavior of the slope was compared to that of an unreinforced slope. The piles significantly increased the stability of the slope and reduced its deformation during an earthquake. The bending moment of the piles exhibited a nearly triangular distribution due to the earthquake. The acceleration response of the slope increased with increasing elevation, and the displacement accumulated apparently irreversibly over the course of the earthquake. The piles significantly affected the deformation of the slope in a certain area, the boundary of which was defined using a continuous surface. A strain analysis of the slope demonstrated that the piles had a significant effect on the reduction in the deformation of the slope in their vicinities, and this effect expanded upward along the slope and arrested the possible slip surface that would have occurred in an unreinforced slope. Several influencing factors were simulated in the tests, and observation of these factors demonstrated that the dynamic response of the pile-reinforced slope was affected by the pile spacing, pile location, slope gradient, and input earthquake to varying extent.
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centrifuge model test study of rainfall induced deformation of Cohesive Soil slopes
2011Co-Authors: Ga Zhang, Jiyun Qian, Rui Wang, Jianmin ZhangAbstract:A rainfall simulation device was developed to realize uniform rainfall at high g-levels in centrifuge model tests. A series of centrifuge model tests was conducted on Cohesive Soil slopes during rainfall, and the displacement and suction of the slopes were measured. The slope exhibits a relatively shallow slide after a heavy rainfall, and exhibits a shear zone with significant deformation in the interior of the slope. The vertical displacement is significantly larger than the horizontal displacement of the slope during rainfall. The rainfall-induced displacement process can be divided into three phases: (1) small displacement, (2) rapid increase, and (3) large displacement with minor rate of increase. Strain analysis was conducted on the basis of the measured displacement, and the results showed that the rainfall-induced deformation of the slope is governed by two types of mechanisms: increasing overburden weight and softening of Soil. For a point in the slope, the first mechanism occurs from the beginning of rainfall; and the second mechanism occurs only when the water infiltrates there, which is described using the wetting front. Accordingly, another term, stable front, describes a boundary of zero increment of deformation. These two fronts gradually advance into the slope with increasing rainfall and divide the slope into three zones. The middle zone exhibits the most significant deformation.
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nail reinforcement mechanism of Cohesive Soil slopes under earthquake conditions
2010Co-Authors: Liping Wang, Ga Zhang, Jianmin ZhangAbstract:Soil nails have been widely used to retain excavations and stabilize steep cutslopes. A series of dynamic centrifuge model tests were conducted on nail-reinforced and unreinforced slopes during an earthquake, with several influence factors, including the nail length, nail spacing, and the inclination of slope, taken into consideration. The unreinforced slope exhibited a progressive failure in the middle and lower parts though the global slip surface did not appear due to the earthquake, which was arrested by using the nail reinforcement. The nails changed the dynamic acceleration response of the slope during the earthquake. The deformation of the slope was significantly decreased by the nails within a nail-influence zone. This zone involved the slip surface of the unreinforced slope, and was almost completely independent on the layout of the nail-reinforcement when the nails had sufficient length. A point couple analysis, a strain analysis, and a uniformity analysis were carried out in an attempt to determine why nails can increase the stability of a slope. It was discovered that the nails forced the deformation of the slope to be more uniform and thus arrested possible strain localization under earthquake conditions. As such, it is suggested that increasing nail length or decreasing nail spacing can both improve the nail-reinforcement effect, and increase the stability level of a slope.