Study On The Technology Of Surrounding Rockcontrol In Floor Roadway Under Repeated Overhead Mining

To keep long-term stability of roadways, the floor roadways are maintained through overhead mining in most of coal mines in China. However, some roadways could keep long-term stability when they were not affected by mining influence. On the contrary, they would be unstable failure and threaten coal mine safety production. Compared with the single coal seam mining, the floor roadway under repeated overhead mining, facing repeatedly overburden mining influence,deformate seriously. General support means is difficult to effectively control the surrounding rock deformation. Therefore, the study on the stability of surrounding rock and the technology of surrounding rock control in floor roadway under repeated overhead mining has great significance.According to Ⅱ2 mining area cross-cut in Luling Coal Mine, which is affected by 8 coal seam and 9 coal seam, by using site investigation, theoretical analysis, numerical simulations and field test methods, the stability of surrounding rock and the technology of surrounding rock control in floor roadway under repeated overhead mining are studied on in this paper.Firstly, based on the actual mining geological conditions in Luling coal mine, by using the theory of semi-infinite elasticity, stress calculation of the stress component under the stope is given in this paper, and the distribution and variation of the surrounding rock are analyzed by the corresponding numerical simulation model. Then, using numerical analysis method of FLAC2 D, the stability of surrounding rock in floor roadway under repeated overhead mining is analyzed, and by the the comparison on activity rhythm among the three different mining influence the instability feature and deformation law of the floor roadway is analyzed. Next, based on the above studies and the stability control principle of surrounding rock in the roadway under dynamic pressure, this paper put forward the reinforcement technology, and the effectiveness of the technology on the surrounding rock control of floor roadway under repeated overhead mining is verified by using numerical simulation measure. At last, according to the geological and mining conditions of Ⅱ2 mining area cross-cut in Luling Coal Mine, using the reinforcement technology with two high strength bolt-mesh-cable, this paper designed the scheme of controlling surrounding rock to conduct site industrial test. Field tracing test data showed that Ⅱ2 new air returning uphill roadway was always under control within allowed range after the overlying coal seam was mining, and the test result was good.