Numerical Analysis of Shallow Foundations Resting on Granular Columns Embedded in Liquefiable Soil

Abstract

Shallow footings are the most preferred foundations for buildings due to low cost and ease of construction. However, under seismic loads, these foundations may suffer excessive settlements, particularly when there is a risk of soil liquefaction. This paper explores the effectiveness of granular columns in mitigating the liquefaction-induced ground deformations under shallow foundations, using FLAC2D program. PM4Sand, a critical state-based bounding surface plasticity model is used to simulate the stress–strain response of sand to cyclic loading. The responses of granular columns are also simulated using the same soil model. Validation of the numerical model is presented against the experimental results of mildly sloping ground. The application of granular column groups resulted in maximum reduction of the settlement of footing by 60% when soil densification is included along with drainage and stress redistribution effects. Though excess pore water pressure is relatively low in treated deposit compared to the untreated deposit, its contribution to the reduction in settlement of footing is found to be minimal.