ABSTRACT
GM (Grey Model) provides an effective way to predict failures of complex systems under conditions
1 INTRODUCTION
Currently, the warning reference for rock safety mainly includes the permissible ultimate displacement, displacement rate, displacement acceleration, deformation ratio and other judging bench marks. It’s hard to use only one single index as a reference to judge the safety of surrounding rock and supporting structure. Sometimes the peripheral displacement goes beyond the reference value of displacement control, but no damage occurs to the supporting structure; sometimes the deformation rate is large, but still far less than the reference value of surrounding displacement control, and no structural damage has occurred; sometimes the rock deformation has not yet reached the reference value of displacement control, but the supporting structure has became instable. Within a certain period of time, the damage of rock will accelerate the destruction (Lian 2012).
