Deformation Failure Law Of Surrounding Rock And Control Technology For Gateway With Variable Width Of The Coal Pillar In Fully-mechanized Caving Face

Analysis of surrounding rock stability, failure mode, failure pattern and its controlling technique of roadway in fully-mechanized sub-level caving mining face is one of key Scientific problem in coal mine supporting. It has important theory sense and engineering applying value to make a research on surrounding rock failure law and its controlling technique of variable-width coal pillars roadway in fully-mechanized sub-level caving mining face. The thesis takes roadway in fully-mechanized sub-level caving mining face in Wei Jiadi Coal Mine of Jing Yuan Coal Corp. as backing, the measures such as indoor and in-situ test, theoretical analysis, FLAC numerical simulation and so on were adopted to study surrounding rock destroying law in mining area of dynamic pressure roadway. The surrounding rock destroying mode was analysed and controlling measures of roadway stability was provided.Under the fully-mechanized exploiting condition of first layer of coal seam in Wei Jiadi Coal Mine, the plasticity area width along inclined coal seam border is 7.8m, the coal pillars width which makes protected coal pillars stable is above 17 m. The vertical stress peak value of coal seam is not couple with horizontal stress peak value. In the narrow to broad changing process of coal pillars, the compressive stress curve in coal pillars according to the law that is"slow mound shape"to"unimodal shape", then to"asymmetric bimodal type", and finally to"asymmetric unimodal shape", and the pressure alteration of roadway roof meet the law of"gradually far away"to"inverted leaping"and finally to"fundamental motionless".Destroying pattern and deformable characteristic with different width coal pillars were obtained, and the optimum coal pillars width in sub-level caving mining face was given. In the narrow to broad changing process of coal pillars, the changing law of coal pillars destroying form is coal pillars all destroyed to"N shape"destroyed to edge shape destroyed to cuneiform destroyed, and the rational width of coal pillars in fully-mechanized sub-level caving mining face in Wei Jiadi Coal Mine is 20m. The roadway stability is transferred according to the pattern of"stable to unsteady to stable"with the increase of coal pillars width.The mechanical mechanism of different consolidating measure controlling surrounding rock deformation of roadway with variable-width coal pillars was analysed. Destroying characteristic of variable-width coal pillars and stability evaluation of roadway were finished, and tunnel anchor net shoring design criteria affected by mining was suggested. Based on the basic theory of informational design, the effective control was suggested to implemented on important location of roadway in key period and synthetical surrounding rock control technique that the consolidation of variable-width coal pillars was given first place and the compound anchor net shoring tunnel is subsidiary was suggested.The three-dimensional finite difference software was applied to carry out the optimization simulation on anchor net shoring scheme, and the rational anchor net shoring parameters can be get. The field practice indicates that the optimization results of anchor net shoring scheme is reasonable and feasible.It has important theory value and actual guiding significance to study the surrounding rock destroying law and supporting technique of roadway with variable-width coal pillars, and it provides science basis to the roadway deformation control under similar condition.