Research on the features of impact damage in roadways in high stress fault structure areas

The coupling effect of static and dynamic stress in fault structure areas exacerbates the risk of rock impact in underground fault areas. The stress distribution law and impact dynamic load response features of roadway surrounding rock in fault structure areas have significant peculiarities. At present, research on the impact of fault structures mainly focuses on the vicinity of the working face, but there is little research on the impact damage of roadways in fault structures. Taking the roadway in a deep buried high stress fault structure area of a mine in Shaanxi Province as the engineering background, the mechanical features of deformation and failure of the roadway surrounding rock in the fault structure area are analyzed. ① There is a significant stress barrier effect on the fault plane, and there are two special stress zones near the normal fault, namely the stress concentration zone in the hanging wall and the stress reduction zone in the lower wall. Due to the influence of the fault plane, the static load concentration stress of the roadway side shows an asymmetric distribution feature. The stress concentration on the side far from the fault plane is greater than that on the side near the fault plane, and the risk of impact damage to the surrounding rock of the roadway on this side increases. ② The fault plane has a significant barrier effect on the transmission of stress waves, and the dynamic load response of the hanging wall of the normal fault is greater than that of the lower wall. Due to the asymmetric distribution of stress on the two sides of the roadway, the dynamic load response of the right side is significantly greater than that of the left side. Based on the above features, a collaborative anti impact control technology of "unloading (large diameter drilling pressure relief) - support (stepped reinforcement into layered energy absorption and anti impact support)" is proposed for the surrounding rock of the fault structure area roadway. The engineering test results show the following points. ① After adopting the "unloading support" collaborative anti impact treatment measures for the roadway surrounding rock , the stress concentration areas of the two sides of the roadway are transferred to the deep part of the surrounding rock by 3-5 meters. The stress peak value is reduced by 18.5%-20.3%, and the stress concentration degree of the roadway surrounding rock is significantly reduced. ② Before the implementation of the "unloading support" collaborative anti impact treatment measures, the deformation of the roadway roof, floor, and two sides are 856, 334, 325, and 567 mm, respectively. The deformation and damage of the roadway surrounding rock are severe. After adopting the "unloading support" collaborative treatment measures, the deformation of the roadway surrounding rock decreases by 35.69%-62.03%, and the stability of the roadway surrounding rock is enhanced. ③ The coal powder content in the borehole is also significantly lower than the critical coal powder content, and the dynamic power of the roadway surrounding rock is reduced.