Numerical Simulation and Risk Assessment of Water Inrush in a Fault Zone that Contains a Soft Infill

A numerical model was established to simulate the activation of the fault zone with a soft infill during a water inrush event. Distribution of the failed areas at different times was acquired. Then, a parametric sweep analysis was conducted to see the influence of permeability. By analyzing the results, a new parameter called the activation coefficient was proposed to characterize the fault zone activation process. A functional relationship was established between the activation coefficient and permeability. A series of numerical cases with different conditions were calculated to determine the parameters in the function. A method to evaluate the risk of water inrush is proposed, based on these results. By comparing the acceptable and actual values of the activation coefficient, the activation speed of the fault zone, and time for excavation and support can be determined; thus, the risk of water inrush can be evaluated. The research results were used during construction of line 1 of the Qingdao subway tunnel engineering project in China, which provided valuable data for assessing the risk of water inrush in a mine.