| The broken characteristics, the movement law, the height of the transmissive fractured belt and the mining subsidence of the overlying strata of a gypsum mine in Hengshan are investigated by similar material simulation experimental method, and the practical surface subsidence was measured. The similar material simulation results show that the overlying strata of the goaf of the gypsum mine begins to produce the vertical transmissive fractured belt and the horizontal transmissive fractured belt between layers when the room span is more than 10 m. The immediate roof of a cantilever beam structure begins to break and gradaully collapses layer by layer with the room span increases, and the first weighting and the periodic weighting of the main roof appears with the room span increases. The surface collapse happens to appearance when the room span is 164 m, and the height of the caving zone and the height of the horizontal transmissive fractured belt between layers are 55 m and 94.5 m respectively, which is 18.3 times and 31.5 times that the height of the goaf. The maximum of the surface subsidence and the range of the influence of the mining subsidence are 115 cm and 342 m, which is good agreement with the measured results, and the relative error between the simulation result and the measured result are 15% and 2.3%. |