This paper presents the experimental and numerical study for analyzing the shear load capacity of geosynthetic encased stone columns (GESC). Past studies on GESC have mainly focused on the vertical load capacity. However, they may also be subjected to significant amount of shear loading for instance, near the toe of high embankments and retaining walls. The shear load capacity of the GESC depends on the diameter of the column, over burden pressure acting on the soil and strength properties of geosynthetic etc. In order to analyze the shear load capacity of GESC, laboratory tests were performed using a large shear box with GESC. The experimental results were compared with those obtained by 3-dimensional numerical modelling using FLAC3D software. The results showed that the geosynthetic encasement provides an additional confinement to the aggregates which leads to improvement in the performance of GESC.

K Rajagopal

Department Of Civil Engineering

Sunil Ranjan Mohapatra

Geotechnical engineering

Numerical models

Soil mechanics

Soils

FLAC3D

Geosynthetics

LARGE SHEAR

SHEAR LOADINGS

Soft clays

Stone column

Soil testing

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability

Stone columns (or granular piles) have proven to be ideal ground reinforcement for supporting flexible structures such as embankments and storage tanks. Stone columns installed in very soft soils will have very low lateral confinement: hence they undergo excessive bulging, leading to undue settlement and limited load-carrying capacity. In these situations, the strength and stiffness of the stone column can be enhanced by encasing the individual stone columns with a suitable geosynthetic. The encasement improves load transfer to deeper depths of soil. This paper investigates the qualitative and quantitative improvement of load capacity of individual encased stone columns through laboratory model tests. These tests were performed in a rigid unit cell that represents the stone column and the soil within the contributary area around the stone column. The load tests indicated a clear improvement in the load capacity of the stone column due to encasement. Encasement with geosynthetics having higher modulus resulted in stiffer response. The effect of encasement was found to decrease with increase in the diameter of the stone column. The improvement in the performance of stone columns was found to be significant, even with partial encasement. © 2007 Thomas Telford Ltd.

Geosynthetics International

Model tests on geosynthetic-encased stone columns

Stone columns (or granular piles) are increasingly being used for ground improvement, particularly for flexible structures such as road embankments, oil storage tanks, etc. When the stone columns are installed in extremely soft soils, the lateral confinement offered by the surrounding soil may not be adequate to form the stone column. Consequently, the stone columns installed in such soils will not be able to develop the required load-bearing capacity. In such soils, the required lateral confinement can be induced by encasing the stone columns with a suitable geosynthetic. The encasement, besides increasing the strength and stiffness of the stone column, prevents the lateral squeezing of stones when the column is installed even in extremely soft soils, thus enabling quicker and more economical installation. This paper investigates the qualitative and quantitative improvement in load capacity of the stone column by encasement through a comprehensive parametric study using the finite element analysis. It is found from the analyses that the encased stone columns have much higher load carrying capacities and undergo lesser compressions and lesser lateral bulging as compared to conventional stone columns. The results have shown that the lateral confining stresses developed in the stone columns are higher with encasement. The encasement at the top portion of the stone column up to twice the diameter of the column is found to be adequate in improving its load carrying capacity. As the stiffness of the encasement increases, the lateral stresses transferred to the surrounding soil are found to decrease. This phenomenon makes the load capacity of encased columns less dependent on the strength of the surrounding soil as compared to the ordinary stone columns. © 2006 Elsevier Ltd. All rights reserved.

Geotextiles and Geomembranes

Geosynthetic-encased stone columns: Numerical evaluation

Journal of Geotechnical and Geoenvironmental Engineering

Behavior of Geotextile-Encased Granular Columns Supporting Test Embankment on Soft Deposit

Geotechnical and Geological Engineering

A Critical Review of Construction, Analysis and Behaviour of Stone Columns

Performance of geogrid-encased stone columns in soft ground: full-scale load tests

Experimental and numerical modelling of geosynthetic encased stone columns subjected to shear loading

Journal	15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability
Publisher	Asian Regional Conference on Soil Mechanics and Geotechnical Engineering
Open Access	Yes