Risk Assessment Method and Practice for Underground Gob Area in Open-pit Mine

Due to the rock weathering, transportation, loading and the factors of blasting vibration effect together, roof collapse happened easily and stability of surrounding rock is declined gradually in small gob area distributed in the scope of open-pit mine, which is a serious safety threat to the ground equipments and workers. Through the analysis and summary of existing research results, then from the viewpoint of system engineering, we proposed the hollow roof collapse estimation method and the minimum thickness estimation method. Combined with the stability evaluation and management practice of underground gob area in Pinshuo Mining Area, stability analysis method and process of a typical goaf is introduced.