| With the rapid development of my country's national economy, the demand for coal continues to increase, the overburden breakage and surface subsidence caused by coal seam mining seriously affect the safety of coal mine production and the ecological environment of the mining area. Mastering the laws of overlying rock breaking and surface subsidence is of great signifence to the reasonable exploitation of coal resources "and the predietion and prevention of disasters in mining areas. Based on the 401102 working face of Hujiahe Minefield, this article ollets the geological and mining data of the mining area, using SBAS-InSAR monitoring tehnology, theoretical analysis, 3 Dimension Distinct Element Code numerical simulation, actual measurement verification and other methods, study the law of surface subsidence during mining in the mining area and the influence of overburden breakage on it.The main research work and results are summarized as follows:(1) The SBAS-InSAR technology is used to monitor the surface subsidence on the top of 401102 working face in Hujiahe Minefield, and obtain its surface subsidence law, The results show that there are two obvious subsidences in the study area, which are located directly above the 401102 working face and the 402 103 working face, and the monitoring results are consistent with the actual situation; In order to quantitatively analyze the law of surface subsidence in the mining process, data were extracted along the direction and inelination of the working face, it was found that as the working face progressed, the surface showed nonlinear settlement, and the settement speed first increased and then decreased, and under the influence of the adjacent 401101 working face goaf, asymmetrical subsidence appeared, and the amount of subsidence on the side close to the old goaf was too large; From October 2014 to July 2016,the maximum surface settlement of 401102 working face in Hujiahe mine field reached 0.609m,and the monitoring results were basically consistent with the measured GPS data.(2)In order to reveal the impact of overburden fracture on the surface subsidence during the mining process,a 3 Dimension Distinct Element Code was used to numerically simulate the 401102 working face.The results show that the surface subsidence caused by mining is the final manifestation of mechanical processes such as overburden movement and fracture on the surface,Among them,the key layer has a controlling effect on the local or overall rock formation,and it is the link connecting the surface subsidence and the breaking of the overburden,the structural state of the main key layer directly affects the surface subsidence.Finally,the simulation results are compared with the InSAR monitoring results and GPS data,and it is found that the simulation results are consistent with the InSAR monitoring results,and the accuracy is reliable.(3)Combined with the numerical simulation results,in order to obtain the surface subsidence more efficiently,aiming at the complex nonlinear relationship between mining subsidence and multiple influencing factors,an adaboost strong prediction model based on particle swarm optimization optimized BP neural network is proposed.The model combines the adaboost algorithm's focus on samples with large prediction errors and the characteristics of particle swarm optimization to optimize neural network weights and thresholds,and achieves the purpose of "selecting the best among the best" strong predictors.This paper uses this model to predict the maximum surface subsidence of the 401102 working face,compared with the numerical simulation results,the relative error is 9.5%,and the prediction results are reliable,indicating that the model is practical in mining subsidence prediction. |
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