Parameter Inversion Of Tunnel Surrounding Rock Based On Differential Evolution Algorithm And Nonlinear Finite Elements

As high degree complexity and uncertainty of geological of the tunnel, it suffered loads and boundary conditions is more complex, and it is difficult to calculate the required parameters accurately. Making both the theoretical analysis or the numerical analysis method is difficult to achieve the desired results, displacement back analysis can effectively solve the bottleneck of "parameters are not allowed ", and gain the wide attention in tunnel engineering.Based on the nonlinear finite element theory and geotechnical elastic-plastic theory, use a new algorithm-return mapping algorithm (Return Mapping Algorithm) in the constitutive equations. Develope a nonlinear finite element program independently. And the finite element program is embedded into differential evolution algorithm, develope an intelligent displacement back analysis procedures (ie EEOS procedures). For before and after the treatment, program the two interfaces for the nonlinear finite element program, First, transform divided grid of the ANSYS into a finite element program for preprocessing documents by programming, Second, transform the finite element results of the stress into the performed data entry in tecplot software, and then display the simulation results graphically, it make the results more intuitive and straightforward.The numerical results and analytical solution is almost consistent according to many example test on EEOS back analysis program.Comparing the control parameters of the different evolutionary algorithm in the back analysis program,obtaining the impact discipline about parameters on the invertion results and convergence rate,which providing the basis for chosing the rational DE parameters.Using the development program named EEOS in Dalian metro engineering, this paper analyses the surface subsidence of specific sections, holes around convergence and valut sink by laiding on-site monitoring points and monitoring the construction data firstly;then back analysis the wall rock parameters by using back analysis program EEOS secondly; thirdly simulates the tunnel excavation on inversion parameters and obtains the future every step plastic zone,stress and displacement.These plays a guiding role in actual engineering.