Analysis Of Overlying Strata And Surface Deformation In Strip Mining Under Thick Conglomerate

Coal resources have long occupied an important position in China's energy field.At the same time,the status of coal as China's main energy source will not change for a considerable period of time in the future.With the extraction of a large amount of coal resources from the ground,a series of negative problems caused by mining,such as surface subsidence and deformation of the goaf,have become increasingly prominent.Strip mining with strata coal pillars supporting the overburden is to slow down the damage and deformation of the overburden.An effective way to control the subsidence of the ground surface,and then to protect the buildings(structures)and ecological environment.In order to effectively control the subsidence of the ground surface,studying the overlying strata and surface deformation regularity of strip mining has become an urgent problem to be solved in mining.This paper takes a coal mine in Shandong as a research background,combined with theoretical analysis,on-site measurement and numerical simulation to study the law of overburden rock and surface deformation under strip mining in thick conglomerate layers.The main work and results are as follows:Observation stations were set up in the study area to carry out the observation of surface movement and deformation.By analyzing the measured data of the surface deformation of the mining face of the mining areas 711,713,715,the maximum surface deformation and rock movement parameters were obtained.According to the existing measured data and geological data,the combination of orthogonal test method and numerical simulation method is adopted,with the maximum subsidence value of the trend observation line A as the test index,the bulk modulus modulus and shear modulus of the three representative strata in the model Parameters such as the amount,internal friction angle and cohesion.Through 27 sets of tests,a set of parameters closer to the measured data was obtained,and an optimal set of rock mechanics parameters was determined.According to the key layer theory,the conglomerate in the overburden of the mining area is judged to be the key layer.Based on the optimal parameters obtained by the orthogonal test,a numerical simulation model is established.The FLAC3D software is used to simulate the surface movement and deformation of the conglomerate layer and the non-concrete layer The influence of conglomerate layers with different thicknesses on the surface and overburden movement law and the distribution law of surrounding rock stress field are also studied.Combining FLAC3D numerical simulation and regression analysis,Simulate the surface deformation of different strip mining schemes under the key layer of conglomerate.The fitting functions between the maximum subsidence value,the maximum horizontal movement value,the subsidence rate and the mining depth,mining thickness,mining width,retention width,and different mining retention widths(the same recovery rate)are determined and analyzes the influence of various factors on the surface movement law.