Vibro Stone Columns with Preloading—An Effective Foundation Solution for Large Storage Structures

The most critical challenge for any large size storage structures to be constructed on soft compressible soils is bearing capacity and consolidation settlements. Consolidation is the time-dependent phenomena, as expulsion of water from soil voids on application of external load will take longer period. It is mainly influenced by soil consistency, permeability, thickness of compressible stratum and presence of free-draining layers. This study deals with the foundation solution of a large size Mounded Storage Vessel (MSV) to be constructed on thick compressible stratum whose loading intensity is around 155 kPa, and the estimated settlements are greater than 400 mm. Hence, the foundation solution using vibro stone columns is adopted as an effective technique to address the challenges of excess settlements and inadequate bearing capacity. Further to keep settlements within the permissible limit of 50 mm, preloading technique with 60% of actual loading intensity will be utilized. The consolidation analysis of stone column-reinforced foundations is carried out based on the method given by Han and Ye (2001). The quality of the stone columns is ensured by real-time quality control measures, and the performance of the stone columns shall be ensured by vertical load tests following IS 15284-Part 1:2003. Ground settlements were closely monitored with proper instrumentations and the actual degree of consolidation has been verified by Asaoka (1978) method.