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. (C) 2016 Elsevier Ltd. All rights reserved.