Analysis of Stiffened Granular Piled Raft

Abstract

Piled rafts are usually provided to reduce total and differential settlements of foundation and structures built on deep deposits of soft or problematic soils. Granular piles may be used in place of conventional concrete or steel piles because of their several additional advantages. The load carrying capacity of these granular piles (GP) can be increased for improved performance by stiffening of granular piles their top portion of length by relatively strong material having better strength and stiffness, i.e. higher deformation modulus in comparison to the material of granular pile in the lower portion. Geogrid encased columns, SDCM (stiffened deep cement mixing), fibre reinforced granular columns, etc. are common forms of stiffening GP. The present study deals with the analysis of partially stiffened granular pile with rigid raft based on the continuum approach. The overall response of the top stiffened GP-raft foundation is evaluated in terms of settlement influence factor, settlement reduction factor in comparison to un-stiffened granular piled raft, normalized GP-soil interface shear stresses, percentage load shared by GP, normalized contact pressure distribution beneath the raft and percentage load transfer to the base of GP with relative stiffness factor and relative length of stiffening.