Influence of district coal pillars recovery on wall rock instability in gob-side entry retaining and the control measures

WANG Jun; YAN Chaochao

doi:10.11799/ce202411007

Abstract：Wall rock stability control of gob-side roadways under repeated mining is an important guarantee to ensure safe mining of the working face using gob-side entry retaining.We took Wulanmulun Coal Mine as the engineering background,analyzed the problem of surrounding rock failure and instability in the roadway layout process,which was transitioning from the original double roadway excavation to the goaf side roadway,during mining in the coal body of No.12408 fully mechanized mining face and the remaining coal pillars between No.12407 working face.By using on-site measurement,theoretical analysis,and numerical simulation methods,the instability response mechanism of the surrounding rock in the goaf side roadway was analyzed,and a multi measure fusion technique was proposed to solve the instability problem of the surrounding rock in the remaining section of No.12408 outer air return roadway.The results show that the main factors leading to the instability of the surrounding rock in the retained roadway are the influence of secondary dynamic pressure superposition,the coupling effect of bedrock lithology characteristics and burial depth,and the irrational matching of tunnel section support strength and mining strength parameters.After adopting a coupled control technology system of reinforcement support,adding unit supports,and rational control of mining speed,the remaining section of No.12408 working face has a roof separation value of 70 mm,a maximum subsidence of 40mm on the roof,and a maximum displacement of 23 mm of both sides toward roadway during the mining process.The overall change is relatively small,and the deformation of the surrounding rock does not affect safe mining.The deformation is within a controllable range.