High-strain dynamic tentative piling technique is the relatively popular pile testing method for obtaining pile soil parameters.The principle is to get the pile-soil parameters using the measured information of pile top.At present

the more mature method is CAPWAPC

by which the pile-soil model parameters are determined using trial and error analysis.The results obtained by CAPWAPC show a certain degree of randomicity

and the correctness of results extremely depends on the experience of operator.With attempts to use the sophisticated pile-soil model in CAPWAPC as foundation

this study uses the local optimization methods of optimal perturbation algorithm to obtain the pile-soil parameters.Perturbation expansion of the parameters and parameter inversion recursive formula are derived and finally the inversion algorithm is proposed based on the implicit elastic wave dynamic differential equations.The influence of initial parameters on local optimization method is adopted in the proposed model

and suitable initial model can be easily established according to the site condition.Results indicate that the proposed method is reasonable for dynamic testing of pile and foundation.