Study on Mechanism of High-strength Water-inrush with Sand Caused by Weak Aquifer in Soft Rock Mining Area

In recent years, there are many cases of high strength water inrush with sand from coal seam roof caused by weak aquifer in Jurassic coalfield in northwest China. In order to identify the mechanism of high-strength water-inrush caused by weak aquifers and sources of sand, to facilitate the development of prevention measures, this paper starts with the analysis of soft rock characteristics, and the viewpoint about the “new four-quadrant” model of the mechanical structure of overburden rock after mining and practical basis are proposed. Four conditions for formation of separated strata water damage are pointed out. It is made clear that the inrush strength of the weak aquifer is strengthened by the catchment action of separated strata, and the self-plugging effect of sediment determines the intermittent water inrush mode. It proves the correctness of the above viewpoints and provides the theoretical basis for the prevention and treatment of such accidents.