FEM inverse computation test study on crushed zone rock mass parameters idenitification

A method for crushed zone surrounding rock mass’ parameters identification in the shallow tunnel engineering is provided in this paper,and the tectonic stress field is not considered in this identification method,because the tunnel is a shallow one,the tectonic stress around the tunnel is too little to count it on.This identification method's computation is based on the elastic-plastic foundation theory and foundation load test.With surveying points' displacement in the load test,the tunnel crushed zone rock mass parameters can be inversely computed out by the FEM inverse theory's genetic algorithm.This method is applied in Jie Pai Au shallow tunnel's crushed zone surrounding rock mass parameters identification.According to Jie Pai Au tunnel's conditions,the tunnel rock foundation load test is carried out and a tunnel surrounding rock mass parameters identification FEM computation model is set up,and then,four basic rock mass parameters including E,μ,c,Φ are inversely obtained.At last,Jie Pai Au tunnel construction steps’ FEM computation model using these surrounding rock mass parameters is set up,and each construction step’s tunnel vault settlement and horizontal convergence are computed.The computation tunnel vault settlement and horizontal convergence are agree to the measured values,which shows that the identified Jie Pai Au tunnel crushed zone surrounding rock mass parameters are credible.