Abstract: It is more likely to cause the collapse of tunnel surrounding rock and water disasters under the action of the coupling effect of the groundwater seepage field, the stress field and the damage field. First of all, surrounding rock is regarded as the isotropic continuum material, and the elastoplastic damage constitutive model of rock is established based on the Drucker Prager criterion. The fully implicit return mapping algorithm is adopted to achieve the numerical solution of elastoplastic damage constitutive equations. Secondly, according to the dynamic evolution formula of permeability coefficient in elastoplastic state based on the above research, the elasoplastic stress-seepage-damage model of rock is established; and the coupling solving iterative method of many fields is presented. Back analysis program is compiled on the basis of the principle of differential evolution algorithm in order to solve the problem that elastoplastic damage model involves many parameters and not easy to determine, and the damage parameters are inversion; Finally, the corresponding coupling program of the elastoplastic stress-seepage-damage is compiled and parameters inversion program are compiled using C++ language respectively. The following calculations are conducted by using the programs: (1) The performance and the correctness of the intelligent back analysis program are analyzed, comparing the inversion accuracy and the convergence rate of the differences between the different strategies, the cross factors and the variation factors. (2) The calculation results of the displacement field and the stress field by the elastic model and the elastoplastic model are compared. (3) The pore water pressure and the seepage flow are calculated without considering the effect of mechanics. (4) The interaction rules of the stress field, the seepage field and the damage field of tunnel surrounding rock are calculated using the coupling model. The results show that the problem of damage parameters which is difficult to determine can be better to solve in damage model by the back analysis program based on differential evolution algorithm. It provides effective method for the calculation parameters are acquired not easily determined in practical engineering. At the same time, the macro failure of rock material can be more realistically reflect through the interaction of the stress, the seepage and the damage of the built coupling model. The calculation program which provides a method for the engineering construction affected by groundwater severely can simulate the coupling characteristics of the groundwater seepage field, the stress field and the damage field. The study of this paper lays a solid foundation for the coupling calculation of the later period for actual tunnel engineering.

Key words: elastoplastic damage constitutive model, permeability coefficient, elastoplastic stress-seepage-damage coupling model, damage parameters inversion