Three dimensional numerical back analyzing seepage parameters of metro tunnel based on difference evolution

Aiming at the uncertainty and underground water of geological body of metro tunnel engineering, the paper proposed a back analysis arithmetic combining three dimensional numerical simulation, orthogonal design and difference evolution. The paper introduced the theory of three dimensional seepage numerical simulation and difference evolution theory, constructed seepage parameters schemes based on thogonal design and uniform design, carried out three numerical tests and obtained the data set for nonlinear fitting and forecast test. The regress function between the coefficient of permeability and monitoring hydraulic heads and flow capacity. Took the difference between numerical calculation value and monitoring data as objective function, adopted difference evolution arithmetic to identify the coefficients of permeability. Adopted the back analysis method to analyze the of permeability coefficients of surrounding rock of Dalian Metro tunnel crossing Malan River, got satisfied results. The arithmetic convergences quickly and the identification precision is higher. Which provided reference for succeeding design and construction.