... CENTRIFUGE AND NUMERICAL MODELLING OF SOFT CLAY- PILE- RAFT FOUNDATIONS SUBJECTED TO SEISMIC SHAKING SUBHADEEP BANERJEE (M.Tech., IIT Roorke) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY ... the effect of the surrounding soft clay was primarily to impose an inertial loading onto the piles, xi thereby increasing the natural frequency of the pile over and above that of the pile foundation ... involving the pile length, moment inertia, pile and soil modulus, mass of the raft and peak ground motion xii Key words: earthquake, pile, soft clay, stiffness degradation, strain softening, resonance...