Abstract：In order to fix limitations of FLAC^3Din building the finite element model for complex environment and specific structures, a new coupling method of MIDAS GTS NX and FLAC^3Dwas put forward. The transition program between modules was compiled by using interface program of Visual Basic. It could modify the node and unit data from MIDAS GTS NX software and creat a *. flac3d file which can be imported to FLAC^3D. A twin-track tunnel in Jingguangnan station of Zhengzhou No. 5 subway has such characteristics as little gabarit, large cross section and drills through underneath a highway tunnel. The main tunnel was excavated by CRD method and support forms were pilot pipes and steel arch support. Taking Zhengzhou No. 5 subway as an example, a model was built based on the engineering, and the transition from MIDAS GTS NX to FLAC^3Dwas successful. The comparison of the calculation results and the field monitoring demonstrated the feasibility and accuracy of the transition method.

Keyword：finite element model;model transition;FLAC3D;MIDAS GTS NX;transition program;