Optimal Foundation System for a Storage Tank in Liquefiable Soil—A Case Study

Abstract

Storage tanks are constructed in all refinery complexes for the bulk containment of fluids at different stages of the refinery process. This paper presents the optimal foundation solution for a storage tank located at Bongaigaon, Assam. Subsoil at the present location consists of top 11 m loose to medium dense silty sand which is further underlain by dense sand with fines content less than 15%. The refinery site is located in the highly seismic prone zone and topsoil up to substantial depth is susceptible to liquefaction. In order to construct a storage tank in such type of soil, it is necessary to provide suitable foundation system for controlling liquefaction and to satisfy the performance requirement. Stone column is one of the ground improvement techniques to increase the bearing capacity and to reduce the total and differential settlements. Ground improvement using vibro stone columns is used to mitigate the liquefaction susceptibility and to minimize the differential settlement of tank foundation. The various aspects of subsoil conditions, design, construction methodology, quality control and hydrotest results are discussed in this paper.