Study On Control Technology About Gob-Side Entry With Top Coal Caving In Incline And Thick Seam Of Chenjiagou Mine

China's extra-thick coal seam mining areas are numerous and large.In recent years,Gob-side entry has been widely used in China to improve coal seam mining rate.The width of coal pillar and the way of supporting are different due to thedifferent geological factors such as coal thickness,inclination angle and ground stress.Extra thick coal seam roadway with thick top coal and multiple layers of thin layered gangues brings a series of problems to the support along the goaf,especially when the inclination of coal and rock strata is more obvious,these problems need to be solved.This paper takes the inclined and thick seam of the Chenjiagou mine as the engineering background.The stability of surrounding rock along the roadway is analyzed from four aspects: surrounding rock property,environment of ground stress,orientation of roadway layout and movement of old roof rock;the reasonable width of coal pillar in roadway along the void is determined by the combination of theoretical calculation and numerical simulation;finally,puts forward the corresponding control technology to control the surrounding rock along the tunnel of Chenjiagou mine,and verifies the rationality of the supporting scheme through the field industrial test.The research has promoted the development of the surrounding rock control technology for fully mechanized caving roadways along Chenjiagou mine,and it has also enriched and developed the surrounding rock control technology and theories for fully mechanized caving roadways along specific conditions.This paper mainly studies as follows:1)Laboratory experiment to determine the mineral composition of rock clay: X-ray diffraction method is used to detect the clay mineral composition in the top coal and the gangue in the empty roadway of Chenjiagou,the result shows: coal rock contains the kaolinite mineral component,and the bearing strength of the roadway surrounding rock is greatly reduced after being cemented.2)Field testing the stress distribution characteristics: The measured in-situ stress results using the sleeve hole stress relief method at three measurement points show that: Horizontal principal stress with obvious directionality is the main part of in-situ stress,and the maximum horizontal principal stress is first delivered to the coal pillar side of the roadway at an angle of 30 °.Therefore,the deformation of the coal pillar side will be greater than that of the solid coal side,and with the increase of the angle between the two,it is easy to induce sliding or shear failure of the roof and floor rock.3)Stability analysis of roadway overburden rock: The discriminating results of the key strata of overburden indicate that,the old roof rock layer is the first sub-critical layer,which has a greater impact on the stability of the roadway.By analyzing the structure of the key block before and after mining in the fully mechanized caving face,it is considered that it provides external large structural conditions for the control along the goaf.On this basis,the reasonable support of the surrounding rock can ensure the normal use of the roadway.4)Analysis of coal pillar width of roadway along goaf: Based on the principle of arranging along the roadway in the coal-body lateral support pressure stress reduction zone,comprehensive consideration of the coordination between the bearing capacity of the coal pillar and the lateral supporting pressure environment,through theoretical calculation and numerical simulation,it is finally determined that the width of the coal pillar remaining in the 8514 roadway is 10 m.5)Control of surrounding rock along empty roadway and industrial test: The asymmetric surrounding rock control technology of high-strength anchor rod + roof length and gradation support with anchoring cable + coal pillar lateral cable anchor + coal pillar grouting is proposed,improve the overall bearing capacity of roof and coal pillars;Field test was conducted in the 8514 roadway of Chenjiagou mine,pressure monitoring results indicate: During the service period,the large deformation of the surrounding rock has been effectively controlled.The paper has together 56 figures,19 tables and 127 references.