Study on the Characteristics of Fracture and Abnormality Mechanism in Comprehensive Mining of Extra-Thick Coal Seam Overburden Rock
In order to determine the mining pressure behaviour law and overburden structure characteristics of the working face under comprehensive mining conditions in extra-thick coal seam,and to study the abnormality mechanism,on-site measurement and numerical simulation methods were used to study the failure situation of the working face and the stress distribution laws under different advancing distances.Based on the internal and external stress field theory and material mechanics,the formation conditions and geometric characteristics of the cantilever beam structure were obtained,and the fracture location of the key layer was quantitatively explored.Physical similarity simulation test was used to verify the key layer fracture state.The results show that the structure of"lower cantilever beam+upper masonry beam"is formed in the key layer under the condition of comprehensive mining in extra-thick coal seam.Fracture length of the cantilever beam is 31.5 m,and the cantilever beam fractures 15.4 m away from the coal wall.The increase of coal seam thickness leads to the rotation deformation and instability of key layer,and ultimately forms the cantilever beam structure,which explains the phenomena of intense mining pressure behaviour in extra-thick seam.
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维普
