Some Studies on Prestressed Reinforced Granular Beds Overlying Weak Soil

J Jayamohan,R Shivashankar

doi:10.5402/2012/436327

Abstract

This paper mainly investigates, from a series of laboratory scale bearing capacity tests carried out on a model square footing, the improvement in bearing capacity and reduction in settlement of a geonet reinforced granular bed (RGB) overlying weak soil due to prestressing the reinforcement. The parameters are the strength of the underlying weak soil, thickness of the granular bed, and magnitude and direction of prestressing force. The settlements at the interface are also measured. The addition of prestress to geonet reinforcement results in significant improvement in the load carrying capacity and settlement response of the prestressed geonet RGB. Improvement in bearing capacity is found to be more with biaxial prestressing than with uniaxial prestressing. Experimental results are also used to validate a proposed numerical model. The BCR (bearing capacity ratio) values predicted from this model are found to be in good agreement with the experimentally obtained BCR values. Finite element analyses are also carried out using the programme PLAXIS, to study the effect of prestressing the reinforcement. Results obtained from finite element analyses are also found to be in good agreement with the experimental results.

Highlights

Soil reinforcing technique, using geosynthetics, has become a major ground improvement technique in geotechnical practice over the last three decades [1]
Shivashankar et al [3] proposed that the improvement in bearing capacity of a reinforced granular bed is comprised of three components, namely, shear layer effect, confinement effect and surcharge effect
The purpose of this paper is to study experimentally the effects of prestressing the reinforcement in granular bed on the load-bearing capacity and settlement response of a reinforced granular bed overlying weak soil and to develop a numerical model to predict the extent of improvement

Summary

Introduction

Soil reinforcing technique, using geosynthetics, has become a major ground improvement technique in geotechnical practice over the last three decades [1]. The use of geosynthetic reinforced granular bed (RGB) over weak soil further reduces settlement and increases the bearing capacity of weak soil. Shivashankar et al [3] proposed that the improvement in bearing capacity of a reinforced granular bed is comprised of three components, namely, shear layer effect, confinement effect and surcharge effect. They proposed equations for computing the effect of each of these components. Deb et al [5, 6] presented a model for the analysis of granular foundation beds reinforced with several geosynthetic layers. An iterative finite difference scheme was applied for obtaining the solution and results were presented in nondimensional form

Objectives

Results

Conclusion