Study On Movement And Deformation Law Of Surface And Overburden In Repeated Mining

Coal mining will cause the movement and deformation of strata and surface,resulting in many geological disasters such as ground collapse.It brings harm to the ecological environment and production work,and the degree of damage caused by repeated mining is higher.So it is very important to select the main parameters when using the probability integral method.In view of the defect that the influence of coal seam dip angle is not considered in the prediction parameters of probability integral method,a modified formula is proposed in this paper.Based on ?2301 and ?2302 working faces in Yuecheng mining area,the surface subsidence after mining is predicted,and the movement and deformation of overburden under the condition of repeated mining are studied by similar simulation test.The main work is summarized as follows:(1)This paper collects relevant data of multiple coal mines,seeks the relationship between the coal seam inclination angle and the predicted parameters through regression analysis,and a correction formula is proposed.According to the revised parameters,the surface movement and deformation values of ?2301 and ?2302 working faces after repeated mining in Yuecheng coal mine are quantitatively predicted,and the movement and deformation law and the influence of repeated mining are analyzed.(2)The similar material simulation test is applied to explore the law of movement and deformation in the process of mining.According to the results,the movement and deformation of strata and the development of cracks are analyzed.The results show that the overburden damage caused by repeated mining is more severe,it also cause the first weighting step smaller,the fracture development height higher,the influence range wider,and the increase of strata subsidence larger.(3)The FLAC3 D numerical simulation method is used to analyze the movement law of surface and strata in the process of repeated mining.The simulation results were compared with the experimental and predicted results to verify the rationality of the model and the accuracy of the predicted results.The results show that the simulation results of strata displacement are close to the similar test results,which indicates that the numerical model is reasonable.Meanwhile,the simulation results of surface displacement have little difference with the predicted results and the maximum error is only 6.3%.Within the allowable error range,the predicted parameters have good correction effect.The research results of this paper have certain guiding significance for predicting surface subsidence and reducing mining damage under similar geological conditions.