Abstract: The surface movement characteristics of coal seam mining in loess hilly terrain are significantly different compared to plain areas. In order to analyze and reveal the anomalous mechanism of coal mining surface subsidence in hilly topography. The surface subsidence caused by top coal caving mining in loess hilly terrain was measured,and the surface movement characteristics and related parameters were analyzed and studied. A 3D model of the considered terrain was established by using the Rhino software and imported into the 3DEC software for numerical simulations. The movement of rock formations during mining and the evolution of plastic damage within the hilly are analysed. The results show that the surface movement of 1313 working face is intense. The starting distance of surface subsidence is less than 30 m. The leading infection distance is 73 m. The leading infection angle is 68. 7°. The strike boundary angle and the upper boundary angle are 40. 3°,and the strike movement angle and upper movement angle are 37. 8°. The dangerous movement range with the horizontal tensile deformation of 2 mm/ m as the movement boundary is significantly larger than the surface movement basin range determined by the subsidence value of 10 mm. Numerical simulation is used to analyze the mining slip process in loess hilly terrain. The results indicted that when the working face is retrieved 30 m along the strike from the open-off cut,the stress equilibrium of the rock around the mining area is broken,and the top plate is shear damaged by the self-weight and the load of the overlying rock layer,and the rock around the mining area is plastic yielded. When the working face is retrieved 120 m,the coal seam is in the non-full mining stage,the shear damage zone of the rock at the bottom of the beam mount is penetrated,and the slope is sheared to the neighboring empty side under the action of gravity. Compared with the section with the surface slope of 15°,the maximum horizontal movement in the negative direction of the X-axis of the section with the surface slope of 18° and 22° increases by 107. 3% and 246. 5%.

Key words: mining subsidence,loess hilly,fully mechanized top coal caving mining,loess landslide,numerical simulation