Nonlinear response of footings on granular bed-stone column-reinforced poor soil

Abstract

In this paper, an attempt has been made to model and analyze the footings, having finite flexural rigidity, lying on granular bed-stone column-reinforced poor soil system. The granular bed placed over stone column reinforced earth beds has been idealized by the Pasternak shear layer. The natural occurring poor soil has been idealized as Winkler springs and stone columns have been idealized as stiffer Winkler springs. Nonlinear behavior of granular bed, natural occurring soil and the stone columns has been considered in the analysis and has been incorporated by means of hyperbolic constitutive relationships. Governing differential equations for the soil-foundation system have been obtained and finite difference method has been adopted for solving these by means of Gauss-Elimination iterative scheme. A detailed parametric study for a combined footing subjected to concentrated column loads at its edges has been carried out to study the influence of various parameters on the flexural response of the footing. These parameters include magnitude of applied load, flexural rigidity of footing, diameter of stone column, spacing of stone column, ultimate bearing capacity of granular fill, poor foundation soil and stone column and relative stiffness of stone columns. It has been found that ultimate resistance of granular fill in shear has negligible effect on the response of soil foundation system. However, other parameters have been found to significantly affect settlement and the bending moment in the footing.