Analysis and risk assessment of main controlling factors of water inrush in shallow coal seam mining under gully
摘要
To investigate the problem of mine water inrush in shallow coal seam mining under gully water body, taking 22104 working face of a coal mine in Ordos as the engineering background, the main controlling factors and risk assessment methods of mine water inrush were studied by using fracture conduction theory model, transient electromagnetic instrument measurement and PFC numerical simulation. The results show that the necessary and sufficient condition for the failure of water inrush fracture is that the sum of the maximum vertical development length (Ha+Hb) of the downward fracture of the gully and the upward fracture of the fracture zone does not exceed their vertical spacing (H), and the sum of the maximum development widths of the two (da+db) does not exceed their horizontal spacing (d). The main controlling factors affecting surface water leakage and water inrush to the working face are the mining height of the working face (M), the spatial relative position of the working face and the gully (vertical spacing H, horizontal spacing d) and the gully occurrence (gully dip angle β, gully depth Hd and gully width L). The mining height directly affects the formation of water inrush fracture channel by controlling the development range of fracture zone and the bending amplitude of gully slope. The relative position of the working face and the gully controls the connection of the water inrush fracture by limiting the interval distance between the upward fracture of the fracture zone and the downward fracture of the gully. The occurrence of gully indirectly affects the formation of water inrush fracture channel by regulating the deformation degree of slope and changing the size of fracture opening in gully. Based on the above conclusions, combined with fuzzy mathematics method, analytic hierarchy process and disaster index method, the risk assessment model of water inrush in shallow coal seam mining under gully water body is established. The risk area and disaster index o