According to the problem of failure and instability in roadbed and cutting engineering of underground karst cavity,on the basis of inhomogeneous elastic damage model,this thesis propose the FEM back-analysis from instability-strength degradation,to describe inhomogeneity of material suppose that the material parameter obeys statistical distribution.

Currently,the stability evaluation of cave foundation is mostly focus on the quantitative evaluation,such as the collapse mechanism and prevention,while the qualitative assessment is rare.