Study On The Surface And Strata Movement Regular Of Mining Under The Hugely Thick Sand

This paper is to study the deformation law of the surface and strata caused by mining under the hugely thick weak cemented sand by numerical simulation and similar material simulation method,basing on the case of 2201 working face of Yingpanhao coal mine.Then identify the key strata of the mining area.The surface subsidence caused by coal mining under the special geological mining conditions is very small,and the height of the collapse fracture zone is higher than experience,which is analyzed theoretically and verified by the measured data.The main research results are followed as:1)According to the surface observation data of the Yingpanhao 2201 working face,this paper found that the surface subsidence is basically in accordance with the general unfully-mined surface subsidence law.But under the geological conditions of the overburden strata of the hugely thick weak cemented sand,the surface subsidence,the sinking speed is obviously small comparing with the eastern coal mine and the western shallow cementing area.2)Basing on the geological mining conditions of 2201 working face in Yingpanhao coal mine,a numerical simulation model for the mining of the hugely weak cementead sand is established to study the movement deformation law of the surface and strata during the process of the working face mining.The simulation results show that the surface subsidence is very small,and the development height of plastic failure is much higher than the empirical value.Then the influence of the thickness of different weak cemented sand and different mining depth on the surface movement deformation was studied.The results of the simulation show that the thickness of the hugely thick weak cemented sand(medium sandstone 2 and kern stone)has a great influence on the surface subsidence.3)This paper studies the movement and breaking characteristics of the immediate roof and the main roof of the gob in the process of coal mining,and analyzes the development and variation of the overlying strata during the mining process by similar materials simulation method,and studies the characteristics of surface movement deformation and the relationship between surface movement and overlying strata movement.The simulation results show that the surface subsidence is very small.When the working face is mined to 780 m,the overlying rock in the goaf is intact shear fall,resulting in a development height of 240 m,far greater than the empirical value.4)The key strata of the Yingpanhao coal mine are identified at last,and the results show that the key layer is multi-layer,and the main key layer is the hugely thick weak cemented sand.According to the distribution of key strata,it is reasonable to explain the abnormal phenomenon of the collapse fracture zone and the surface subsidence in the numerical simulation and similar material simulation experiment,which is verified by measured data.The main key layer causes the surface subsidence to be very small,and the collapse fracture zone is much larger than the empirical value.5)The surface measured data shows that the surface subsidence of 2201 working surface is basically in accordance with the general non-sufficient surface subsidence law.Based on the research results of surface movement observation of adjacent mines,it can be seen that the surface movement law caused by underground coal mining is basically in accordance with the probabilistic integral method model.On this basis,the probability integral method prediction parameters of 2201 working surface of Yingpanhao coal mine are determined by analogy to the measured parameters near the surface of the well field.