Trapezoidal collapse model to calculate the height of the overburden collapse zone in coal seam mining: An example from Guo'Jiahe Coal Mine, Western China

In view of the fact that water inrush often occurs from head-on roof of working face, on the identical time, sand-burst and mud-burst accidents even occur in the process of mining the Jurassic Coal Seam, which is formed in one of the three main coal forming periods in China. Guided by the practical theory of mine pressure control, taking the two disastrous water inrush accidents that occurred head-on in 1309 working face of Guojiahe Coal Industry Co., Ltd. as an example, the mechanisms of head-on water inrush in the working face are respectively revealed for fracture line type, i. e. Then deduced the roof overburden collapse zone's evolution law because of coal seam mining and the stress state of the roof settlement process. A trapezoidal collapse model was proposed to evolve the overburden collapse zone after coal mining to describe the overburden collapse and fissures' evolution and calculate the collapse zone's height. The model accuracy was verified using numerical simulation, 3D high-density electric prospecting and measured data of different coal mines. • A new theoretical model was proposed to solve the problem of roof water inrush in coal mining. •The fracture development form of the trapezoidal collapse model was discussed, and the fracture development space was calculated. •The formulas for calculating the height of overburden collapse zone under two failure modes are derived and compared.