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Sanjay Kumar Shukla - One of the best experts on this subject based on the ideXlab platform.
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ultimate bearing capacity of strip footing resting on soil bed strengthened by wraparound Geosynthetic Reinforcement technique
Geotextiles and Geomembranes, 2020Co-Authors: Sanjay Kumar Shukla, Muhammad Nouman Amjad RajaAbstract:Abstract In the recent past, the wraparound Geosynthetic Reinforcement technique has been recommended for constructing the Geosynthetic-reinforced soil foundations. This paper presents the development of an analytical expression for estimating the ultimate bearing capacity of strip footing resting on soil bed reinforced with Geosynthetic Reinforcement having the wraparound ends. The wraparound ends of the Geosynthetic Reinforcement are considered to provide the shearing resistance at the soil-Geosynthetic interface as well as the passive resistance due to confinement of soil by the Geosynthetic Reinforcement. The values of ultimate load-bearing capacity determined by using the developed analytical expression agree well with the model footing load test values as reported in the literature.
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Influence of Geosynthetic Reinforcement on Unpaved Roads Based on CBR, and Static and Dynamic Cone Penetration Tests
International Journal of Geosynthetics and Ground Engineering, 2020Co-Authors: Meenakshi Singh, Ashutosh Trivedi, Sanjay Kumar ShuklaAbstract:Dynamic cone penetrometer has been used widely as a pavement evaluation technique for many years. Unpaved roads constructed on weak soil subgrade are frequently subjected to severe damage and hence, they require regular maintenance and repair. One of the main stabilization methods of improvement of the serviceability of these roads is to reinforce them with Geosynthetics (geotextile/geogrid). Field experiments were conducted on unpaved test sections reinforced with geotextile and geogrid, with the potential use of dynamic cone penetrometer (DCP) and digital static cone penetrometer (SCP) to assess benefits of geotextile and geogrid Reinforcement. Laboratory California bearing ratio (CBR) tests were also conducted on subgrade–aggregate section and the effect of Geosynthetic Reinforcement was investigated by placing the Reinforcement layer at the interface of the base course layer and weak subgrade. Digital SCP was used to measure the load–displacement behavior of Geosynthetic-reinforced test section in the field. The field test results of DCP were expressed in terms of dynamic cone penetration index (DCPI, mm/blow), defined as the penetration depth of the cone per hammer blow and recorded along with the depth profile. A decrease in DCPI value was observed for the reinforced test sections as compared to the unreinforced test section. DCP results were able to detect transition zone and significant change in the strength of unpaved test section along with penetration depth. The field results indicate the greater resistance to penetration in the Geosynthetic-reinforced test section and the penetrometer resistance increases with the depth. Higher penetration resistance offered by the geotextile has more contribution to the performance improvement of the test section.
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optimum burial depth of Geosynthetic Reinforcement within sand bed based on numerical investigation
International Journal of Geotechnical Engineering, 2020Co-Authors: Shadi Aria, Sanjay Kumar Shukla, Alireza MohyeddinAbstract:In model studies as well as in field projects, the burial depth of a Geosynthetic Reinforcement layer within a sand bed is often assumed to be approximately 0.3 times the width of the footing. Howe...
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strength enhancement of the subgrade soil of unpaved road with Geosynthetic Reinforcement layers
Transportation geotechnics, 2019Co-Authors: Meenakshi Singh, Ashutosh Trivedi, Sanjay Kumar ShuklaAbstract:Abstract Geosynthetic Reinforcement layers are often used to improve the performance of pavement structures. The performance of an unpaved road is routinely measured in terms of the California bearing ratio (CBR), which is an index of strength of subgrade soil of unpaved road. In the present study, an experimental investigation was carried out to evaluate the performance of the subgrade soil by placing a single layer and double layers of Geosynthetic Reinforcements (Glasgrid, Tenax 3D grid and Tenax multimat) horizontally at varying depths from the top surface of subgrade soil. Through a series of CBR tests in the laboratory, an attempt was made to determine the optimum depth of the Reinforcement layer. The single layer of Reinforcement has been placed at the middle, one-third and one-fourth of the height of the CBR specimen from the top surface of the soil in the CBR mould. The double layers of Reinforcement were placed at one-fourth of the specimen height from the top surface and the bottom surface. The results show the significant contribution in terms of increased CBR value of the soil, resulting in reduced design thickness of the pavement layers above the subgrade soil. It has been observed that for a single layer Reinforcement the Tenax 3D grid performs better than other Geosynthetics used in this study while the Tenax multimat performs best for double layers. The results indicate that for the maximum benefit, the Tenax 3D grid Reinforcement should be placed in between 0.3H and 0.36H where H is the height of the soil specimen. For Glasgrid and Tenax multimat Reinforcements, the maximum effect of Reinforcement is obtained when they are placed between 0.41H and 0.62H.
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Analytical Investigation of Load Over Pipe Covered with Geosynthetic-Reinforced Sandy Soil
International Journal of Geosynthetics and Ground Engineering, 2019Co-Authors: Sanjay Kumar ShuklaAbstract:A Geosynthetic Reinforcement layer can be placed above the pipe in a ditch within the sandy soil cover to reduce the load on the crown of the pipe. The vertical load ( V ) on the crown of the rigid pipe without the Geosynthetic layer is given as $$V={C_{\text{d}}}\gamma {B^2}$$ V = C d γ B 2 , where $$\gamma$$ γ is the total unit weight of sandy soil, B is the ditch width and $${C_{\text{d}}}$$ C d is the load coefficient. The analytical formulation for load on the crown of the pipe covered with a single layer of Geosynthetic-reinforced sandy soil has been developed earlier. In this paper, an attempt is made to derive an analytical formulation to investigate the load coefficient for pipe covered with sandy soil reinforced with two layers of Geosynthetic Reinforcement. It is observed that the two layers of Geosynthetic Reinforcement provide more benefits than a single-layer Reinforcement in terms of the load reduction on the pipe. It is also noted that the stiffness of Geosynthetic, buried depth, layer spacing and rut depth affect the load on the crown of the pipe. An illustrative example is presented in order to explain how the engineers can determine the load on the pipe using the analytical expression presented in this paper.
S. Chandra - One of the best experts on this subject based on the ideXlab platform.
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Extensible Geosynthetics and stone-column-reinforced soil
Proceedings of the Institution of Civil Engineers - Ground Improvement, 2010Co-Authors: Prabir Kumar Basudhar, S. ChandraAbstract:The present study involved the development of a mechanical model to study the behaviour of extensible-Geosynthetic-reinforced granular fill resting on stone-column-improved soft soil. The stone column, Geosynthetic layer, soft soil and granular fill were idealised by stiffer Winkler springs, rough elastic membrane, Kelvin–Voight model and Pasternak shear layer, respectively. Plane strain conditions were considered in the analysis. An iterative finite difference procedure was applied to obtain the solutions and the results are presented in non-dimensional form. The results indicate that inclusion of the Geosynthetic layer (inextensible or extensible) effectively reduced the total as well as the differential settlement. However, the use of inextensible Geosynthetic Reinforcement was more effective than extensible Geosynthetic Reinforcement to reduce settlement and increase the stress concentration ratio.
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Slippage effect on the settlement response of a granular soft soil system
2009Co-Authors: A. Al-adili, S. Chandra, Nagaratnam SivakuganAbstract:In this paper a numerical study using the finite element method is undertaken to predict the settlement response of a footing, considering plane strain conditions, resting on a reinforced granular bed on soft soil. The granular fill, soft soil and Geosynthetic Reinforcement are considered as non linear materials. The Geosynthetic Reinforcement is modelled with interface elements for allowing slip between the soil and Reinforcement. The results obtained from the present investigation showed close agreement when compared with the results of finite element analysis and lumped parameter modelling carried out by previous researchers, assuming no slip conditions. The number of Reinforcement layers was taken as one or three (multilayer). A parametric study has been carried out to illustrate the effect of slippage of the Reinforcement layer on the settlement response. The increase in the settlement is not significant when the slippage of the Reinforcement is considered.
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generalized model for Geosynthetic reinforced granular fill soft soil with stone columns
International Journal of Geomechanics, 2007Co-Authors: Prabir Kumar Basudhar, S. ChandraAbstract:This paper pertains to the development of a mechanical model to predict the behavior of a Geosynthetic-reinforced granular fill over soft soil improved with stone columns. The saturated soft soil has been idealized by Kelvin — Voight model to represent its consolidation behavior. The stone columns are idealized by stiffer springs. Pasternak shear layer and rough elastic membrane represent the granular fill and Geosynthetic Reinforcement layer, respectively. The nonlinear behavior of the granular fill and the soft soil is considered. Effect of consolidation of the soft soil due to inclusion of the stone columns has also been included in the model. Plane strain conditions are considered for the loading and reinforced foundation soil system. An iterative finite difference scheme is applied for obtaining the solution, and results are presented in nondimensional form. Comparison between the results from the present study and the analytical solution using theory of elasticity shows reasonable agreement. The advantage of using Geosynthetic Reinforcement is highlighted. Results indicate that inclusion of the Geosynthetic layer effectively reduces the settlement. Nonlinearity in the behavior of the soft soil and the granular fill is reduced due to the use of Geosynthetic Reinforcement layer.
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Settlement response of a multilayer Geosynthetic-reinforced granular fill–soft soil system
Geosynthetics International, 2005Co-Authors: S. Chandra, Prabir Kumar BasudharAbstract:The paper pertains to the development of a mechanical model to predict the behaviour of a multilayer Geosynthetic-reinforced granular fill soft soil system. The granular fill and the soft soil have been idealised as a Pasternak shear layer and a layer of non-linear springs, respectively. Stretched rough elastic membranes represent the Geosynthetic Reinforcement layers. The non-linear behaviour of the granular fill and the soft soil is considered. Plane strain conditions are considered for the loading and reinforced foundation soil system. An iterative finite difference scheme is applied for obtaining the solution, and the results are presented in non-dimensional form. The results of the present model are compared with the results of a finite element model. Parametric studies for a uniformly loaded strip footing show the effects of various parameters on the settlement response. Significant reduction of the settlement has been observed as a result of the use of the multilayer Geosynthetic Reinforcement syst...
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settlement response of a multilayer Geosynthetic reinforced granular fill soft soil system
Geosynthetics International, 2005Co-Authors: S. Chandra, Prabir Kumar BasudharAbstract:The paper pertains to the development of a mechanical model to predict the behaviour of a multilayer Geosynthetic-reinforced granular fill soft soil system. The granular fill and the soft soil have been idealised as a Pasternak shear layer and a layer of non-linear springs, respectively. Stretched rough elastic membranes represent the Geosynthetic Reinforcement layers. The non-linear behaviour of the granular fill and the soft soil is considered. Plane strain conditions are considered for the loading and reinforced foundation soil system. An iterative finite difference scheme is applied for obtaining the solution, and the results are presented in non-dimensional form. The results of the present model are compared with the results of a finite element model. Parametric studies for a uniformly loaded strip footing show the effects of various parameters on the settlement response. Significant reduction of the settlement has been observed as a result of the use of the multilayer Geosynthetic Reinforcement syst...
Muhammad Nouman Amjad Raja - One of the best experts on this subject based on the ideXlab platform.
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ultimate bearing capacity of strip footing resting on soil bed strengthened by wraparound Geosynthetic Reinforcement technique
Geotextiles and Geomembranes, 2020Co-Authors: Sanjay Kumar Shukla, Muhammad Nouman Amjad RajaAbstract:Abstract In the recent past, the wraparound Geosynthetic Reinforcement technique has been recommended for constructing the Geosynthetic-reinforced soil foundations. This paper presents the development of an analytical expression for estimating the ultimate bearing capacity of strip footing resting on soil bed reinforced with Geosynthetic Reinforcement having the wraparound ends. The wraparound ends of the Geosynthetic Reinforcement are considered to provide the shearing resistance at the soil-Geosynthetic interface as well as the passive resistance due to confinement of soil by the Geosynthetic Reinforcement. The values of ultimate load-bearing capacity determined by using the developed analytical expression agree well with the model footing load test values as reported in the literature.
G M Filz - One of the best experts on this subject based on the ideXlab platform.
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effectiveness of Geosynthetic Reinforcement for load transfer in column supported embankments
Geosynthetics International, 2020Co-Authors: Michael P Mcguire, Joel A Sloan, G M FilzAbstract:Many column-supported embankment (CSE) design methods include Geosynthetic Reinforcement for vertical load transfer and/or settlement reduction regardless of project conditions. However, geosynthet...
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Column-Supported Embankments: Settlement and Load Transfer
Geotechnical Engineering State of the Art and Practice, 2012Co-Authors: G M Filz, Michael P Mcguire, Joel A Sloan, James Collin, Miriam E. SmithAbstract:Column-supported embankments (CSEs) can reduce settlements, improve stability, and prevent damage to adjacent facilities when embankments are constructed on ground that would otherwise be too weak or compressible to support the new load. Geosynthetic Reinforcement is often used to help transfer the embankment loads to the columns in CSEs. This paper addresses three important design issues for CSEs: (1) the critical height above which differential settlements at the base of the embankment do not produce measurable differential settlements at the embankment surface, (2) the net vertical load on the Geosynthetic Reinforcement in the load transfer platform at the base of the embankment, and (3) the tension that develops in the Geosynthetic Reinforcement. Based on bench-scale tests, field-scale tests, and case history data, the critical height was found to be a linear function of the column spacing and the column diameter. The net vertical load that acts down on the Geosynthetic Reinforcement can be determined using the load-displacement compatibility method, including determination of the limiting stress distribution at the base of the embankment by a generalized form of the Adapted Terzaghi Method, which accommodates any column or pile cap shape, any repetitive column arrangement, and different soil types in the load transfer platform and the overlying embankment fill. The tension in the Geosynthetic can be calculated using a generalized form of the parabolic method, which incorporates stress-strain compatibility and which accommodates rectangular and triangular column arrangements and biaxial and radially isotropic geogrids.
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A Generalized Formulation of the Adapted Terzaghi Method of Arching in Column-Supported Embankments
Geo-Frontiers 2011, 2011Co-Authors: Joel A Sloan, G M Filz, James CollinAbstract:Design of Geosynthetic-reinforced column-supported embankments requires calculation of the reduced load on the Geosynthetic Reinforcement due to arching within the embankment fill. The load on the Geosynthetic Reinforcement is then used to calculate the tension in the Geosynthetic Reinforcement of a given strength and stiffness. Russell and Pierpoint (1997) proposed a method for calculating the load on the Geosynthetic Reinforcement in column-supported embankments based on Terzaghi's (1943) theory of arching. Their expression is developed for square columns in a square arrangement with homogeneous embankment fill material. This method shows reasonable agreement with instrumented embankments and numerical results presented in the literature but is limited to specific column geometry and homogeneous fill. Other column arrangement patterns include rectangular, equilateral triangular, and isosceles triangular, and the columns themselves may also be round. Some column-supported embankment design methods also specify a select fill material at the base of the embankment prior to placing general embankment fill material in order to further promote arching. This paper presents a method for calculating the load on the Geosynthetic Reinforcement in column-supported embankments for generalized column and unit cell geometry and two layers of embankment fill with differing material properties and lateral earth pressure coefficients.
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analysis of Geosynthetic Reinforcement in pile supported embankments part iii axisymmetric model
Geosynthetics International, 2010Co-Authors: R H Plaut, G M FilzAbstract:ABSTRACT: In the first part of this study, the Geosynthetic Reinforcement in a pile-supported embankment was modelled as a thin plate, and in the second part it was modelled as a cable net. Three-dimensional analyses were conducted. A notable feature of the results was the existence of spikes in strains and stresses near the edges of the pile caps, particularly near corners. The computational effort was significant. In this last part an axisymmetric model is analysed, which is simpler, and yields approximate results. It is most appropriate for circular pile caps, but can also be used to estimate displacements for square pile caps. The Geosynthetic is modelled here as a membrane with linear stress–strain response, and the governing equations allow for large strains and slopes. The finite difference method is utilised, and the total energy is minimised to obtain equilibrium shapes. For two cases, the effects of Poisson's ratio, soil stiffness, stress concentration ratio, average embankment stress, area repl...
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analysis of Geosynthetic Reinforcement in pile supported embankments part i 3d plate model
Geosynthetics International, 2010Co-Authors: B M Jones, R H Plaut, G M FilzAbstract:ABSTRACT: Geosynthetic Reinforcement over a grid of piles in soft soil can help transfer loads to the piles, and reduce settlements. This first part of a three-part study utilises a three-dimensional thin-plate model of the Geosynthetic. The von Karman theory, which includes the effects of bending and stretching, is used. The Geosynthetic layer is represented using a linear stress–strain relationship. Owing to symmetry, a one-eighth triangular section of a square unit cell is considered, and the pile caps have either a square, diamond or circular shape. The soil between the pile caps and the Geosynthetic, and the soft soil between the piles, are modelled as linear foundations with specified stiffnesses. The embankment stresses over the piles and over the soft soil are also specified. The numerical procedure involves finite differences and minimisation of the total energy. For two sets of parameter values, the effects of the shape of the pile caps on the displacements, strains and net stress reduction rati...
Kerry R Rowe - One of the best experts on this subject based on the ideXlab platform.
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numerical study of the effects of Geosynthetic Reinforcement viscosity on behaviour of embankments supported by deep mixing method columns
Geotextiles and Geomembranes, 2015Co-Authors: Kerry R RoweAbstract:Abstract The influence of Reinforcement viscosity on the post-construction performance of embankments with floating columns and fully penetrating columns is explored. It is shown that the viscous behaviour of Geosynthetic Reinforcement can increase the long-term shear deformations of foundation soil and increase the horizontal toe movement. The effects of Reinforcement strain at the end of construction of embankments over two soft clay deposits are investigated. The deep-mixing-method column supported embankments with viscous and with inviscous Reinforcement are numerically constructed to identify the effect and magnitude of Reinforcement creep and stress relaxation.
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effects of viscous behavior of Geosynthetic Reinforcement and foundation soils on the performance of reinforced embankments
Geotextiles and Geomembranes, 2008Co-Authors: A L Li, Kerry R RoweAbstract:Abstract The combined effects of viscoelastic behavior of Geosynthetic Reinforcement and viscoplastic nature of rate-sensitive foundation soils on the performance of reinforced embankments are investigated. The variation of viscoelastic properties is examined using Geosynthetic products that are made of polyester, polypropylene and polyethylene. The foundation soils consist of two soft clay deposits with different strain-rate sensitivities. Embankment construction is numerically simulated to identify the magnitude of creep deformation of the Reinforcement and the foundation soil under both limit state and working stress conditions and the consequent effects on the stability of the embankment. It is shown that the creep of Geosynthetic Reinforcement and foundation soil can decrease the short-term stability of embankments and that the mobilized Reinforcement stiffness and corresponding tensile force can be significantly lower than that measured from standard laboratory test. The isochronous stiffness can reasonably represent the mobilized Reinforcement stiffness at the critical stage of the embankment. During post-construction periods, Reinforcement strain can increase substantially and it has shown that the increase in Reinforcement strain is largely due to the viscoplastic behavior of foundation soils. The mobilized Reinforcement strain under working stress conditions with respect to Reinforcement stiffness are also discussed.