Deformation Mechanism And Its Control Of Roadway Surrounding Rock Under Intensive Mining In Extra-thick Coal Seams At 10 Million Fully-mechanized Top Caving Faces

The extra-thick coal seam mining areas are widely distributed.With the continuous improvement of mechanization,intelligence and intensification of coal mine production,the mode of 10 million ton fully mechanized top coal caving face in one mine site has developed rapidly,which has brought technical problems of deformation control of the surrounding rock of roadways under the conditions of intensively dynamic pressure,multiple disturbances and large deformation,which seriously affects the safe and efficient mining of fully mechanized top coal caving working face in extra-thick coal seam.The fundamental reason is that the evolution law of mine pressure within the influence range of mining advance of fully mechanized top coal caving face in extrathick coal seam is not clear,the mechanism of strengthening support of mining roadway in fully mechanized top coal caving face in extra-thick coal seam is unknown,and the deformation and failure mechanism and control technology of surrounding rock of intensive mining roadway in fully mechanized top coal caving face in extra-thick coal seam are studied.It has important theoretical significance and engineering value for the safe mining of 10 million ton fully mechanized top coal caving face in extra-thick coal seam.Therefore,the two key scientific issues of the overlying rock structure evolution law and the roadway surrounding rock failure mechanism of fully mechanized top coal caving face in extra-thick coal seam were focused.This paper adopts the methods of field investigation,experimental test,theoretical analysis,numerical simulation,similar material simulation and field measurement to carry out the structural load transfer of the overlying strata of the intensive mining roadway,the deformation of the surrounding rock of the intensive mining roadway,the strong support system for rapidly increasing impedance and high unbalanced load and its effect evaluation method,etc.The research results have been applied in 5110 return air roadway of Tashan Coal Mine,and the following innovations were achieved.(1)The spatial geometric effects and stress flow superimposition characteristics of intensive mining in a typical ultra-thick coal seam of 10 million tons level are analyzed,and a mechanical model of Winkler elastic foundation composite beams with unequal lengths is established,and the super-thickness is obtained.The intensive mining roadway in fully mechanized top coal caving face is characterized by wide pressure range and high stress concentration coefficient.(2)The asymmetric transmission mechanism of the roof load of the intensive mining roadway in the fully mechanized caving face of extra-thick coal seam is revealed.The analysis shows that the intensive mining roadway presents the characteristics of high eccentric load stress distribution.The strain energy density factor is used to characterize the intensive mining roadway surroundings.The characteristics of rock energy evolution give the key main controlling factors for the deformation of the surrounding rock in the intensive mining roadway.(3)Asymmetric strong support method for the surrounding rock of intensive mining roadway of fully mechanized caving face in extra-thick coal seams was proposed,a new type of rapid increase in resistance and high unbalanced load of single pillar with a support resistance of 600 k N was developed.The anchor,mesh and column joint control system of intensive mining roadway rock was successfully applied in the field.There are 108 figures,22 tables and 117 references in this dissertation.