Study On The Protection Scope Of Protective Layer Of Yutianbao Coal Mine Based On Physical Similar Simulation

China’s coal seam is often in the form of coal seams,coal mining is often accompanied by the danger of gas outburst,protective layer mining as an effective safety mining technology,is the most effective regional outburst measures.According to the protective layer of mining mechanism,the protective layer of mining research is the key to the scope of protection.Based on the actual background of the Yutianbao coal mine project,the orthogonal test of the influence of the three factors and four levels on the physical and mechanical properties of the similar material is carried out.The re-use test conclusion is applied to the physical protection Similar simulation test study,through the measurement of the amount of deformation of the deformation of the protective layer to protect the scope of protection.And then through the field inspection test to get the protection of the mine under the protective layer,and then the experimental data and field data to be compared analysis.The main results and conclusions of this paper are as follows:(1)The physical and mechanical properties of similar materials were studied by three-factor four-level orthogonal test,and the degree of influence of sand ratio and residual water content on the physical and mechanical properties of similar materials was determined.The results show that the sand-The influence of compressive strength and elastic modulus is the most significant,and the residual water content has the greatest influence on Poisson’s ratio.According to the results of the study and the actual formation conditions,the similar materials with similar physical conditions are obtained by adjusting the three factors,Which laid the foundation for the physical similar simulation test of the lower protective layer.(2)Using the results of similar material ratio test,the similar materials of simulated strata in Yutianbao coal mine are obtained and similar simulation tests are carried out.The expansion and deformation of overburden in the goaf of the lower protective layer after excavation are obtained State and model collapse after the stability of the "three bands" features.(3)The stress and strain values of the measuring points measured by similar simulations are obtained.The stress curve and the relief angle of the protective layer are obtained.The unloading angle is 92 ° in the uphill direction and the unloading angle Is74 °.(4)In the field of Yutianbao coal mine,the unloading angle of the protective layer in the 5 # coal seam was 88 °,and the unloading angle in the downhill direction was73.4 °.The results of the similar simulation experiment were investigated.The results are compared,and the protection range is basically the same,which shows that the protection range is reliable by the indoor physical similar simulation test.The influence of similar materials on the physical and mechanical properties of similar materials is more accurate by orthogonal test of different materials at different levels of similar materials,and this method is used to compare large-scale similar simulation experiment materials,which can improve the large-scale similar simulation test...