The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform

Mohammad Yousuf Shah - One of the best experts on this subject based on the ideXlab platform.

  • Three Dimensional Numerical Study on Behavior of Geosynthetic Encased Stone Column Placed in Soft Soil
    Geotechnical and Geological Engineering, 2020
    Co-Authors: Lateef Ahmad Dar, Mohammad Yousuf Shah
    Abstract:

    Ordinary stone column (OSC) reinforced soft soils undergo excessive settlements under vertical stresses due to the lack of adequate lateral support from the surrounding native soil. To overcome this issue, stone columns are suitably encased by a Geosynthetic Material having high axial stiffness, which provides the required additional confinement. A numerical analysis aimed at analyzing the effect of Geosynthetic encasement on the load settlement behavior of Geosynthetic encased stone columns (GESC) under vertical stresses is presented. Three dimensional (3D) models were developed in PLAXIS3D to simulate the behavior of stone column reinforced soft soils using the unit cell idealization concept. The numerical models were first validated with the help of experimental data of model tests on GESCs from literature. Various parameters were varied to quantify their impact on the load settlement behavior under column only loaded condition. The parameters varied include the diameter of GESCs, spacing to diameter (S/D) ratio, pattern of stone column installation, Geosynthetic encasement stiffness, length of encasement, length of floating column, cohesion of soil and friction angle of stone column infill. Increase in the diameter of GESCs led to increased settlement for a particular vertical load intensity. The bearing capacity improved with increase in the Geosynthetic stiffness, encasement length, length of floating GESCs, the cohesion of soil and the friction angle of the stone column infill. Increase in S/D ratio decreased the bearing capacity and triangular pattern of stone column installation was found to be more efficient. Moreover, the lateral bulging indicated a reducing trend upon increasing the axial stiffness of encasement.

  • Deep-Seated Slope Stability Analysis and Development of Simplistic FOS Evaluation Models for Stone Column-Supported Embankments
    Transportation Infrastructure Geotechnology, 2020
    Co-Authors: Mohammad Yousuf Shah
    Abstract:

    Inclusion of stone columns in the underlain soft soil is one of the most prominent methods for improving the stability of embankments. The stone columns are encased with a Geosynthetic Material to further enhance the stability. The influence of this partial replacement of weak foundation soil with stone columns on the performance of embankments needs to be quantified. In this study, performance of ordinary stone column (OSC) and Geosynthetic-encased stone column (GESC)–supported embankments is carried out using a three-dimensional finite element programme (PLAXIS3D). A parametric study was conducted to quantify the influence of various factors viz. spacing to diameter ratio (S/D), stiffness of encasement, cohesion of soil, friction angle of stone column and friction angle of embankment on the factor of safety against deep-seated failure. The results show that encasing the stone columns enhances the stability of embankments. Decreasing the column spacing (S/D) enhances the stability, reduces the excess pore pressure development and average settlement. Increase in geotextile encasement stiffness, cohesion of underlain soft soil, friction angle of stone column and friction angle of embankment improves the performance of embankments and also reduces the average settlement of the ground under embankment. Results of the parametric study were used to develop two types of data-driven models viz. multiple linear regression (MLR) and artificial neural networks (ANN) to simplify the evaluation of the factor of safety (FOS) of embankments. Among the two approaches, ANNs were able to predict the factor of safety values more accurately.

Lateef Ahmad Dar - One of the best experts on this subject based on the ideXlab platform.

  • Three Dimensional Numerical Study on Behavior of Geosynthetic Encased Stone Column Placed in Soft Soil
    Geotechnical and Geological Engineering, 2020
    Co-Authors: Lateef Ahmad Dar, Mohammad Yousuf Shah
    Abstract:

    Ordinary stone column (OSC) reinforced soft soils undergo excessive settlements under vertical stresses due to the lack of adequate lateral support from the surrounding native soil. To overcome this issue, stone columns are suitably encased by a Geosynthetic Material having high axial stiffness, which provides the required additional confinement. A numerical analysis aimed at analyzing the effect of Geosynthetic encasement on the load settlement behavior of Geosynthetic encased stone columns (GESC) under vertical stresses is presented. Three dimensional (3D) models were developed in PLAXIS3D to simulate the behavior of stone column reinforced soft soils using the unit cell idealization concept. The numerical models were first validated with the help of experimental data of model tests on GESCs from literature. Various parameters were varied to quantify their impact on the load settlement behavior under column only loaded condition. The parameters varied include the diameter of GESCs, spacing to diameter (S/D) ratio, pattern of stone column installation, Geosynthetic encasement stiffness, length of encasement, length of floating column, cohesion of soil and friction angle of stone column infill. Increase in the diameter of GESCs led to increased settlement for a particular vertical load intensity. The bearing capacity improved with increase in the Geosynthetic stiffness, encasement length, length of floating GESCs, the cohesion of soil and the friction angle of the stone column infill. Increase in S/D ratio decreased the bearing capacity and triangular pattern of stone column installation was found to be more efficient. Moreover, the lateral bulging indicated a reducing trend upon increasing the axial stiffness of encasement.

Madhavi G Latha - One of the best experts on this subject based on the ideXlab platform.

  • bearing capacity of square footings on Geosynthetic reinforced sand
    Geotextiles and Geomembranes, 2009
    Co-Authors: Madhavi G Latha, Amit Somwanshi
    Abstract:

    The results from laboratory model tests and numerical simulations on square footings resting on sand are presented. Bearing capacity of footings on Geosynthetic reinforced sand is evaluated and the effect of various reinforcement parameters like the type and tensile strength of Geosynthetic Material, amount of reinforcement, layout and configuration of Geosynthetic layers below the footing on the bearing capacity improvement of the footings is studied through systemati model studies. A steel tank of size 900 x 900 x 600 mm is used for conducting model tests. Four types of grids, namely strong biaxial geogrid, weak biaxial geogrid, uniaxial geogrid and a geonet, each with different tensile strength, are used in the tests. Geosynthetic reinforcement is provided in the form of planar layers, varying the depth of reinforced zone below the footing, number of Geosynthetic layers within the reinforced zone and the width of Geosynthetic layers in different tests. Influence of all these parameters on the bearing capacity improvement of square footing and its settlement is studied by comparing with the test on unreinforced sand. Results show that the effective depth of reinforcement is twice the width of the footing and optimum spacing of Geosynthetic layers is half the width of the footing. It is observed that the layout and configuration of reinforcement play a vital role in bearing capacity improvement rather than the tensile strength of the Geosynthetic Material. Experimental observations are supported by the findings from numerical analyses.

  • Investigations on Sand Reinforced with Different Geosynthetics
    Geotechnical Testing Journal, 2006
    Co-Authors: Madhavi G Latha, Vidya S Murthy
    Abstract:

    This paper presents results of triaxial compression tests on sand reinforced with different types of Geosynthetics in different layer configurations to study the effect of quantity of reinforcement and tensile strength of the Geosynthetic Material on the mechanical behavior of Geosynthetic-reinforced sand. The reinforcement types used are woven geotextile, geogrid, and polyester film. The layer configurations used are two, three, four, and eight horizontal reinforcing layers in a triaxial test sample. From the triaxial tests, it is found that the Geosynthetic reinforcement imparts cohesive strength to otherwise cohesionless sand. The effect of reinforcement on the friction angle was found to be insignificant. The magnitude of imparted apparent cohesion is found to depend not only on the tensile strength of the Geosynthetic Material but also the surface roughness changes during loading. Special triaxial tests using rice flour as the reinforced medium, microscopic images, and surface roughness studies revealed the effect of indent formation on the surface of polyester film, which was the reason for the unusually high strength exhibited by the sand reinforced with polyester film.

Veeraragavan Amrithalingam - One of the best experts on this subject based on the ideXlab platform.

  • an investigation on the interface bond strength of Geosynthetic reinforced asphalt concrete using leutner shear test
    Construction and Building Materials, 2018
    Co-Authors: Nithin Sudarsanan, Rajagopal Karpurapu, Veeraragavan Amrithalingam
    Abstract:

    Abstract The application of Geosynthetics between the cracked asphalt pavement layer and new asphalt layers to retard reflective cracking has gained interest in the past decades. The performance of the interlayer system depends on its capacity to bond between the old and newly laid overlay layers. This study is taken up to evaluate the interlayer bond strength between the asphalt pavement layers that is reinforced with a Geosynthetic product impregnated with asphalt as a tack coat Material. Three Geosynthetic reinforcement Materials made of coir, jute, and glasgrid are used for the bond strength evaluation. The strength of the unreinforced (UR) interface samples are also evaluated for comparison. A trial pavement section was constructed to obtain the reinforced and unreinforced samples for the current research work. The main objective is to study the effects of these Geosynthetic products at different temperatures on the interface shear strength behaviour of the reinforced asphaltic concrete layer. Leutner shear tests are employed for the estimation of the shear strength of these samples. The tests are performed at five different temperatures, −10, 0, 10, 20 and 30 °C to understand the thermal effects on the composite interface in the pavement. The shear tests conducted at a strain rate of 50 mm/min shows an increase in strength by 10–15% with change in temperature from −10 to 10 °C followed by 80% reduction in strength up to 30 °C. It is observed that the shear strength of the Geosynthetic-reinforced interface samples reduces by 20–50% compared to the unreinforced samples depending upon the type of Geosynthetic Material. This paper proposes an equation to predict the Leutner shear strength at any temperature varying from −10 to 30 at the studied range of strain rates knowing the peak shear modulus of unreinforced samples at −10 °C and the reduction factor for the Geosynthetic interlayer.

Aria Shadi - One of the best experts on this subject based on the ideXlab platform.

  • Load-settlement and stress-strain behaviour of geotextile-reinforced sandy soil
    Edith Cowan University Research Online Perth Western Australia, 2018
    Co-Authors: Aria Shadi
    Abstract:

    During the past few decades, many studies have been conducted to investigate the load-settlement behaviour of Geosynthetic-reinforced foundations, and researchers proposed different methods to improve the performance of Geosynthetic-reinforced foundation soils as well as to develop empirical equations to estimate their bearing capacity. In the recent past, using geotextile reinforcement with wraparound ends has been recommended to strengthen the foundation soil aimed at improving the effectiveness of using Geosynthetic reinforcements. However, there are still areas that received far too little attention in the past, e.g. the optimum geometric parameters in Geosynthetic-reinforced sandy soils with or without using wraparound reinforcement technique. An optimal design and the effectiveness of employing Geosynthetic Material for strengthening the foundation soil require an extensive knowledge of the load-settlement behaviour and failure mechanism of reinforced soils. This thesis presents extensive laboratory measurements and numerical analysis conducted to (i) investigate the effect of angle of internal friction of soil on the optimum burial depth of the reinforcement and the bearing capacity of the Geosynthetic-reinforced sandy soil based on numerical modelling, (ii) study the effects of reinforcement geometrical parameters, namely land width occupied by the reinforcement, and the lap length of the wrapped ends, based on numerical modelling, (iii) present experimental evaluations of the effectiveness of the wraparound reinforcement technique for improving the bearing capacity and load-settlement characteristics of sandy soils, and (Das & Sivakugan) study the strain distribution and the mobilisation of tensile modulus in geotextile reinforcement buried within the sandy soil. In the experimental phase, laboratory model strip footing tests were performed to investigate the influence of wraparound lap length and occupied land width on the load-settlement behaviour of sandy soil. In addition, an instrumentation program with pressure cells and strain gauges was designed to investigate stress and strain distribution within the sand bed. The test results show that the existence of wraparound ends of the geotextile reinforcement improves the bearing capacity of sand bed by about 70% comparing with reinforced foundation soil without wraparound ends. The strain distribution observations reveal that the theoretical solution may overestimate the tensile strength of the geotextile in the range of 30-60 % that can be due to the in-isolation methods being used by standards to measure the tensile modulus of Geosynthetics. In the numerical phase, first, a numerical model was built to investigate the effect of the angle of internal friction of sand on the optimum burial depth of Geosynthetic reinforcement. Numerical outputs reveal that the optimum burial depth depends significantly on the angle of internal friction of sand, and has a linear relationship with the height of the active wedge beneath the footing. In the second stage, a parametric study of the wraparound reinforcement technique was carried out to investigate the effects of geometrical parameters of wraparound reinforcement on the bearing capacity of the sandy soil. The model was used to critically analyse the reinforcing mechanisms for improved bearing capacity caused by wraparound ends. The results reveal that the efficiency of reinforced models with wraparound ends in terms of occupied land area is about 100% higher than that of without wraparound ends. The research carried out as presented in this thesis demonstrates that the wraparound Geosynthetic reinforcement technique can be highly beneficial in a location of limited land width for foundation construction