Influence of Multiple Layers of Encasement on Bulging Capacity of Granular Column

Improvement of debilitated ground by strengthening it became the demand of construction industry and granular columns performs a satisfactory role in achieving the requirements. Granular columns have been used as the part of substructure for higher stiffness of ground, which influences overall compressibility of ground and causes lesser settlement of superstructure. Encasement of granular column further improves the efficiency of load transfer system, utilizes the bulging resistance to the nobler level together with intervening soil. In this paper an attempt is made to study the influence of multiple encasement layers on load carrying capacity offered by bulging of the granular column. In the laboratory model, various types of granular columns were installed in soft clay bed i.e. without encasement, with single layer encasement (SLE) (at the boundary of granular column) and with multiple layers of encasements (MLE). Load tests were conducted by loading the column area and unit cell area for each case. The behavior of bulging area and its impact on the stiffness is studied. The tests results indicate that the load carrying capacity of granular columns installed in soft clay bed with multiple encasement increases substantially in comparison with ordinary and single layer encasement.