Kalman filtering & FEM coupling back analysis method considering broken zone and its application to stability analysis of surrounding rock

Considering the mechanics status of the excavated surrounding rock and the uncertainty essence of many problems in rock mechanics, the Kalman filtering & FEM coupling back analysis method considering broken rock zone is established and programmed in Fortran. Using the interactive communication technology between Fortran and VC++based on the operating files, the back analysis module is added into the Tunnel Construction Monitoring Management and Surrounding Rock Stability Intelligent Analysis Software System for one hand; and the back analysis and surrounding rock stability analysis is realized conveniently and visually based on the graphics module of the system developed by ourselves for the other hand. After the initial parameters have been worked out based on the Kalman filtering & FEM coupling back analysis method considering broken rock zone, the maximum shear strains of the global calculating field are obtained based on FEM. And then, by comparing with the critical shear strain obtained by experiment and theoretical deduction, the stability of the surrounding rock could be judged. Because the method mentioned above discards the unreasonable hypothesis of the initial stress field, the results are more practicable and reasonable. The method has been successful applied to the Baiyun tunnel YK48+737; and the changing plastic zone distribution figures through time are obtained. The on site designers and builders would be able to know the stability situation of the surrounding rock in time, and improve their design and construction.