Influence of fracture-induced weakening on coal mine gateroad stability

The ground stability of gateroads is a major concern in underground coal mines, especially when the surrounding strata are weak and fractured. This paper presents a novel numerical modelling technique for gateroad stability analysis based on a case study conducted at Zhaogu No. 2 mine, China. Considering the occurrence of fracturing and its weakening effect on the stiffness of the rock mass, a tension-weakening model is implemented into FLAC3D, whereby the stiffness of the rock mass is progressively decreased with the failure state. A relationship between the intensity of fractures and the residual strength of the rockmass is built in the numerical model. A parametric study of the tension-weakening model is carried out, and the results are compared to elastic-perfectly plastic and strain-softening models. It is shown that the tension-weakening model exhibits noticeable effects on ground deformation and rock support loading, which are observed from field measurements. Thus, the tension weakening model offers a more realistic simulation of the gateroad behavior than elastic-plastic and strain softening models. The proposed model can be utilized for other applications involving rock reinforcement of mine openings under similar geotechnical conditions.