Study On In-situ Nondestructive Testing Method Of Nonlinear Foundation Model Parameters Of Anti-collision Structural Pile Foundation And Tool Development

Different from the traditional pile foundation which mainly bears the axial load,the anti-collision pile foundation is mainly used to bear the transverse load.Nonlinear foundation model is commonly used for pile foundation,and determining the parameters of the nonlinear foundation model is a key step in the research of the pile foundation.At present,although there are such methods that can be used for confirming nonlinear foundation model parameters as field test method,laboratory model test method,soil test method and expert experience method,they cannot meet the requirements of in-situ nondestructive testing.This paper presents an in situ nondestructive testing method for the nonlinear foundation model parameters of the collision-resistant pile foundation.In-situ nondestructive testing can be conducted on nonlinear foundation model parameters of anti-collision structural pile foundation by this method.First,take the nondestructive testing method of dynamic signal processing as reference,the Winkler foundation model constituted by nonlinear spring and viscous damping was used to simulate the constraint effects of soil around pile on pile.The transverse loading pile was taken as Euler-Bernoulli girder,and the dynamic finite element model of pile foundation under transverse impact load effects was established to gain the dynamic response of pile foundation under the effects of transverse impact load.Finally,taking the minimization of the dynamic time bending distance RMS between the pile foundation dynamic response simulation results and the measured results as the objective function,the value on nonlinear foundation model parameters as design variables,the optimization design model is established.The parameters of nonlinear foundation model are obtained by genetic algorithm.Second,take highway guardrail column as an example,the finite element model of hammer hammer pile foundation was established,and the results show the feasibility of the in-situ nondestructive testing In order to facilitate the popularization of this method,the GUI module in MATLAB software was used to carry out the visual interface design for the inversion identification method of model parameters.Finally,in order to reduce the influence of uncontrollable factors on inversion parameters,some uncontrollable factors were considered in engineering practice.In this paper,the parameters obtained from the inversion identification were taken as the reference,and the parameters of the foundation model were designed with the Taguchi design method,so as to obtain the optimal combination of model parameters.The in situ nondestructive testing method combining inversion identification and robust design can accurately obtain the nonlinear foundation model parameters of the pile foundation.Compared with the traditional parameter determination method of nonlinear foundation model,this method has low cost and high accuracy,so it can be widely used in engineering practice.