FEM Calculation Of Non-stationary Creep Constitutive Model Of Rock Mass And Displacement Back Analysis

Under the function in such factors as water and weathering, etc. some mechanical parameters of rock body such complicated material change obviously over time, for example such parameters as Young's modulus and intensity reduce with growth of time, this fact has already proved to test in room. But at present, during the mechanical calculation of rock mass project, mechanical parameters that the constitutive model adopts are stationary, namely all mechanical parameters have nothing to do with time, they do not change with growth of time. This artificial simplified assumption does not accord with the actual conditions, and influences directly the forecast of deformation convergence and the evaluation of reinforcement measures of rock body project.This article introduces non-stationary parameters to describe the damage progress, namely damage evolutionary process, works out the corresponding finite element procedure, and combines the simple problems with analytic solution to confirm the program; then the application feasibility of the finite element non-stationary visco-elastic displacement back analysis algorithm is examined based on the analysis of an classic case; at last according to the non-stationary visco-elastic constitutive model makes displacement back analysis of a real tunnel of projects. The result indicates that non-stationary visco-elastic constitutive model more directly and objectively reflects viscous secular attribute of rock mass, and more accurately forecasts secular deformation behavior of engineering rock mass in the later practice stage.