SEISMIC RESPONSE OF PILE GROUPS UNDER OBLIQUE-SHEAR AND RAYLEIGH-WAVES

A simple analytical solution is presented to calculate the pile-soil-p ile interaction and eventually the dynamic response of pile groups whe n excited by the passage of Rayleigh waves and obliquely incident SH-w aves. A dynamic Winkler model, with realistic frequency-dependent 'spr ings' and 'dashpots' in conjunction with physically motivated approxim ations is utilized to compute the wave field radiating from an oscilla ting pile and the effect of this field on an adjacent pile. The couple d rocking motion of the pile group resulting from Rayleigh waves and t he torsional motion of the pile group resulting from SH-waves is accur ately predicted by a simple mathematical expression, The results of th e presented method can be obtained with 'hand calculations' and are in excellent agreement with results from 'rigorous' solutions based on i ntegral equation formulations. It is found that the group response is primarily affected from the phase difference of the input seismic moti on at the location of each pile (wave-passage effect). Pile-soil-pile interaction has insignificant effect and can be neglected.