Settlement Behaviour of Very Soft Soil Reinforced with Stone Columns

Abstract

Construction on soft soils has always been a problem to geotechnical engineers. A review of the literature reveals that many techniques and methods have been developed to work with such soils. The technique of soft soil improvement by the installation of stone columns has become popular in recent past and has proven its application to many construction situations in soft soils. Construction of stone columns provides a new composite ground consisting of stiff stone column–soil matrix. Stone column reinforcement in the soft ground increases the bearing capacity and improves the settlement characteristics. They can be used to accelerate the rate of consolidation of soft soil deposits through a well-understood mechanism. They act as vertical drains that provide a shorter drainage path for excess pore water pressure to dissipate rapidly. In the present investigation, an attempt has been made to study the settlement characteristics of soft soil reinforced with the stone column. The main objective of the study was to investigate the settlement time behaviour of the stone column in very soft soil having undrained shear strength (cu) ≈ 5 kPa under different bearing pressures and to verify the results of the experimental results with the analytical theory on consolidation rate of composite ground. A compactive effort is applied during the construction of stone column, and its average value is equal to 21.98 kJ/m3. The settlement of the reinforced soft soil bed is reduced by 25.8% when reinforced with stone column diameter of 76.2 mm.