Parametric fitting of soft soil sites' Davidenkov model based on PSO algorithm and its application

Here, to explore applications of Davidenkov model in seismic response analysis of soft soil sites, the incremental shear modulus expressions for Davidenkov model's nonlinear dynamic constitutive model in initial loading, unloading and reloading stages were derived, and the soil body's dynamic stress-strain relationship was extended to 3-D. Then, parameters of Davidenkov model were fitted using the particle swarm optimization (PSO) algorithm and the fitting program was compiled with MATLAB. The applicability of the method was verified through fitting test data of typical sand and clay. Parameters of a certain typical Shanghai soft soil site were fitted. Afterward, using the secondary development platform UMAT provided with ABAQUS, the subroutine for the nonlinear dynamic constitutive model of soft soil body based on Davidenkov model was compiled, and the correctness of the subroutine was verified through a complex loading path. Finally, taking a certain typical Shanghai soft soil site as an example, the calculation results based on the nonlinear dynamic constitutive model and those using the equivalent linearization method were contrastively analyzed. The results showed that parameters of Davidenkov model can be well fitted with the PSO algorithm; the subroutine of the nonlinear dynamic constitutive model proposed here can better describe nonlinear behaviors of soft soil sites; acceleration response values and relative displacement response ones of the typical Shanghai soft soil site based on the nonlinear dynamic constitutive model are smaller than those using the equivalent linearization method. © 2019, Editorial Office of Journal of Vibration and Shock. All right reserved.