A new rock fracture reconstruction method under the constraints of microseismic location and focal mechanism

Under mining conditions, rock masses can experience progressive damage that leads to fracture initiation, propagation and coalescence and thus trigger fracture-controlled disasters, which are dynamic and complex. Therefore, the dynamic characterization of three-dimensional (3D) fractures is critical for revealing disaster-causing mechanisms of rock masses and preventing disasters and has become one of the important problems in the engineering rock mass. This paper proposes a new 3D rock discrete fractures reconstruction method that incorporates microseismic (MS) event location and focal mechanism constraints. The proposed method incorporates a statistical outlier removal (SOR) algorithm, a Gaussian mixed model with expectation maximization (GMM-EM) algorithm for MS events clustering, an intensity-weighted total least square (IWTLS) algorithm for fracture fitting, and moment tensor inversion (MTI) method for fracture orientation optimization. In addition, laboratory uniaxial compression tests with acoustic emission (AE) monitoring were conducted to verify the applicability of the proposed method. Finally, the proposed method was applied to an iron mine with water inrush disasters. The formation process and distribution characteristics of fractures that control water inrush channels were analyzed, and formation mechanisms of water-conducting fractures induced by the mining were determined. The proposed method helps to characterize the dynamic evolution of fractures during rock mass failure under mining disturbance and provides a new idea for recognizing the failure mechanism of rock masses and calibrating water inrush channels.