Distribution of Stress on Stone Column-Reinforced Soft Soil under Cylindrical Storage Tank

Abstract

Structures with circular foundation (chimney, silo, oil tank) constructed on compressible soft soil, often have to opt for ground improvement like stone columns before construction. In this paper, the stress distribution on stone column-reinforced ground under cylindrical storage tank has been presented. Actual foundation soil reinforced with stone column is assumed as composite ground of soil and hollow cylindrical stone rings keeping the area ratio constant to carry the analysis in axi-symmetric condition. The soft soil, stone columns and granular fill are idealized using mechanical elements. The floor slab of the storage tank is assumed to be flexible enough to satisfy the theory of thin plate. Governing differential equations are derived to determine the vertical settlement and solved with finite difference technique. Contact stress at ground level is calculated from vertical settlement. It is observed that soft soil experiences heavy settlement and contact stress when the tank is full despite of low spacing to diameter ratio (S/dc = 3) and reasonable modular ratio (Ec/Es = 20). It is also observed that stress acting on edge stone column is lower as compared to the stress acting on center stone column even under uniformly loaded condition.