PILE-TO-PILE INTERACTION IN THE TIME-DOMAIN NONLINEAR AXIAL GROUP RESPONSE UNDER HARMONIC LOADING

An approximate, physically motivated procedure to compute the non-line ar axial response of single piles and pile groups under harmonic loadi ng is presented. The method utilizes a non-linear shaft model in conju nction with a time domain formulation for the propagation of waves emi tted from the periphery of each pile, to account for pile-to-pile inte raction. The shaft model involves standard geotechnical parameters. Yi elding of the soil surrounding the pile and slippage along the pile-so il interface are modelled separately. The model is calibrated using da ta from well-instrumented full-scale experiments, Hysteretic damping i s modelled through non-linear distributed springs governed by the Bouc -Wen model, whereas radiation damping is approximated with frequency-d ependent distributed dashpots. It is assumed that non-linear behaviour is confined to the near vicinity of the pile-soil interface and that the soil in between piles remains linearly viscoelastic. Plane-strain theory of wave propagation is utilized and an attenuation function in the time domain is derived to approximate the influence of motion of o ne pile on another A qualitative study of non-linear effects on pile-g roup response is presented. It is observed that nonlinear behaviour su ppresses pile-to-pile interaction, while reducing the equivalent stiff ness and increasing equivalent damping.