基于最佳摄动量法的桩基承载力反演

通过高应变动力试桩法来获得桩土参数是目前比较流行的试桩方法,其原理主要是通过以桩顶的实测信息来反演桩土参数,其中比较成熟的CAPW APC法主要用试凑法来反演桩土模型参数,其反演结果呈现一定的随机性且正确性过于依赖操作者经验。本文尝试以CAPW APC法所采用比较成熟的桩土模型为基础,引入基于最佳摄动量法的局部优化方法来反演桩土参数。在弹性波波动方程隐式差分的基础上,对反演参数采用摄动展开并推导出参数反演的递推公式,最后给出合适的反演算法。考虑到初始参数对局部优化方法的影响,根据场地的实际情况选取合适的初始模型,计算显示可以获得比较理想的结果,说明本法是对桩基动测方法的一种有效的新尝试。

Optimal Perturbation Algorithm and Its Application in the Pile Bearing Capacity Inversion

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.