Abstract: Because of the deep embedding, high underground pressure and fragmentation of ore and rockmass, the Xiaoguanzhuang Iron Mine is one of the most difficult excavation iron mine in China. The study results in recent years indicate that the rockmass of Xiaoguanzhuang Iron Mine has the creep characteristic. After the roadway was excavated, the destruction of supporting roadway is very severe. The deformation of roadway is no convergence deformation; and the iron mine is difficult support mine. According to the field condition, in order to know the distribution law of underground pressure, we used the rock failure process analysis (RFPA), in which the creep evolvement model is drawn into the numerical model, to model the excavation process of roadway by adopting the non-pillar sublevel caving; and numerically analyze the stress distribution of surrounding rock. We found that the surrounding rock occur the creep deformation along with time when the roadway is caving. Because of the creep deformation of roadway, the destruction of roadway is mainly rib spalling, floor heave and roof falling etc.. At the same time, the high stress concentration leads to the severe destruction of pillar between two roadways. Along with the caving of roadway, the stress diverts into surrounding roadway of the newly caved roadway. Because of the multi-step caving, the high stress convergence occurs in the boundary ores, which leads to the difficult excavation of boundary ore. The numerical result is in accordance with the result of field investigation. From the numerical result we concluded that the creep characteristic of rockmass and the multi-step excavation mainly lead to the destruction of roadway.

Key words: underground pressure, non-pillar sublevel caving, roadway, background stress field