Study of the Motion Path of Water-Intercepting Aggregate in a Coal–Rock Mass Water Gush Roadway

After water gushing occurs in a coal mine roadway, abundant aggregate needs to be perfused into the water gush roadway to establish a water interception section and reduce the current velocity. Clarifying the water-intercepting aggregate motion path and quantitatively calculating the displacement distance are critical for determining perfusion hole spacing. This paper employs the CFD-DEM coupling approach, which is capable of accurately characterizing the water gush continuous flow properties and the aggregate discrete motion behavior. This can be used to simulate and analyze the water-intercepting aggregate motion in a water gush roadway, categorizing it into three phases: free fall, curvilinear projectile, and sliding. The theoretical motion model aggregate can be developed, and the calculation formulas for aggregate motion distances in each phase derived. A parameter test scheme was designed and combined with numerical simulation methods to verify the accuracy of the formulas. Finally, based on this research, it is proposed that the theoretical model can be used to dynamically optimize the design of perfusion hole spacing, maximizing the synergistic effect of multi-hole perfusion. The selection of aggregate density and size should ensure the vector sum of the aggregate motion distance in phase II and III approaches zero, thereby improving the water-intercepting efficiency.