Comparison of end-of-drive and restrike signal matching analysis for a real case using continuum numerical modelling

Abstract

The main objective of this paper is introducing a so-called continuum numerical model to overcome some of the limitations of the mass–spring–dashpot systems. Two continuum numerical schemes including a finite difference method (FDM) and a finite element method (FEM) are utilized. Unlike the previous continuum numerical models, the adopted models follow a signal matching procedure similar to lumped models. A real driven pile that has been carefully monitored is considered for model verification and validation, for which the dynamic and static test results, soil profile and soil characteristics are available. Among the major advantages of the model are considerations of soil inertia and/or radiation damping effects. A signal matching procedure is followed by changing the strength and deformation parameters of the soil and interface between pile–soil, both at the “End-Of-Drive” (EOD) and “Beginning of Restrike” (BOR). The results indicate a substantial increase in the soil strength parameters of the pile–shaft interface and the soil modulus below the pile tip at restrike. It is found that the effect of radiation damping significantly changes the pile–soil stiffness during pile hammering. The comparisons between FDM and FEM predictions show very good agreements. Two sets of parameters involved in signal matching are introduced for EOD and BOR signal matching analyses, to compare the variations during the soil setup process. The parameters are also compared against the in situ soil parameters acquired from soil investigation data.