Study on multi-fields catastrophe evolution laws of water inrush from water-rich fault in excavation roadway

Water inrush from faults is one of the major safety issues threatening the safety of Coal Mines. In water-rich fault inrush, the fault is both the water-inrush channel and the source for water inrush. It poses great harm to mining operation but can be very disguising. In order to better understand this major mine hazardous factor, the authors carried out a thorough study on water inrush accidents at Hongcai Coal Mine, a fluid-solid coupling analysis model and a non-Darcy Forchheimer N-S nonlinear turbulence seepage model is established. Numerical simulation is applied to reconstruct the dynamic process of water-rich fault inrush in the development roadway. The coupled evolution of stress field, displacement field, and seepage field through out the process of water inrush disaster are analyzed, and the effective multivariate information features of water inrush precursors are extracted. This study found out that water-rich fault inrush was the combining result of excavation disturbance and hydraulic pressure in the fault fracture zone. During this process, the multi-field information in the aquiclude changes continuously, which can be divided into three stages: the stage of initial change with the developing face far away from the fault, the stage of rapid change with developing face getting closer to the fault, and the stage of abrupt changes. During the process of water inrush, groundwater flows into the roadway from top to bottom along the fault fracture zone with the pressure continuously decreasing along the runoff path;And the overall trend of flow velocity is increasing with decreasing taking place as the water inrush entering the channel and roadway, before it starts increasing again, and the velocity and pressure gradually come to stabilize after water finally enters the roadway. Before the water inrush is induced in the aquiclude fault, the stress of surrounding rock undergoes continuous increasing before falling down, the displacement of surrounding rock increases sharply after a period of stable building-up; a noticeable increase in the water pressure in fault is observed as it approaching the fault, but decreases right before the water inrush is about to take place. This study helps to deepen the understanding of the evolution process of flooding caused by water inrush at the water-rich fault, and provides a scientific basis for determining the precursor characteristics of water inrush.