Analytical and numerical evaluation of the effect of stiffening with the rigidity of bearing stratum on the reduction of settlement for a partially stiffened granular pile

A traditional approach of using granular pile (GP) is an economical and effective technique to achieve the objectives of ground improvement. If GP is partially stiffened from the top of GP, their overall performance gets improved. Stiffening of GP can be achieved by replacing partially the upper portion of GP with a material having superior mechanical properties, e.g. by geosynthetic encased columns, SDCM (stiffened deep cement mixing), etc. Analyses of a single partially stiffened (SPS) floating and end-bearing GP is presented in this paper in terms of settlement influence factor (SIF) for the top of GP, settlement reduction factor (SRF), percentage load shared by the base (PLSB) of GP. Analytically the variation of normalised shear stress (NSS) distribution along the length of the partially stiffened GP is presented in this paper. SIF for the top of GP was found to decrease, while the PLSB of GP was found to increase, with an increase in the stiffening parameters viz. stiffening factor (SF) and the percentage length of stiffening (PLS) from top of GP for a partially stiffened GP.