Dynamic Monitoring and Research on the Evolution of the Damage of Weakly Consolidated Coal Floor under Dynamic Pressure Using Distributed Optical Fiber

During the extraction of coal seam, the evolution pattern of the rock is an important element for controlling the rock seam and preventing water damage to mine. In order to obtain the deformation and damage of weakly cemented coal seam footings under dynamic pressure, the stability of the footings was studied using a combination of various methods, including rock mechanics testing, field testing, and numerical simulations. By sticking distributed optical fiber on the surface of rock samples, the degree and location of rupture on the surface of rock samples could be obtained using the strain response correlation for optical fiber. Two monitoring holes were arranged in the bottom plate of coal seam at 12307 working face of a mine in Ordos Basin, China. Moreover, a distributed optical fiber sensor was implanted in the hole. The results show that the failure depth was 16.5 m. On the other hand, the numerical simulation results show that the failure depth of the bottom plate was 16.0 m, which agreed well with the measured value. The distribution characteristics of the maximum principal stress of the bottom slab during the advancement of working face were obtained using three-dimensional (3D) numerical model. Based on the distributed optical fiber strain tests in the two boreholes in the same vertical profile and combined with the natural proximal interpolation method, the interhole strain increment distribution profile was obtained. The research results provide a reference for the safe mining of coal resources and the prevention and control of water damage in the mine floor.