Roadway repair technology of broken surrounding rock under residual coal pillar for close distance coal seams

Aiming at the problems that underlying surrounding rock of roadway of residual coal pillar was crushed seriously and repaired difficultly,which influenced by the concentrated stress of coal pillar in the process of close distance coal seam mining,basing on the engineering background of a mine in Shanxi province,the stress distribution law of coal pillar floor was analyzed by numerical simulation method and the causes of deformation and failure of surrounding rock were summarized which based on the actual deformation characteristics of roadway.It was found that the concentrated load in the floor of residual coal pillar distributed homogeneously,leading to the destruction of support bearing structure which was the root cause of large deformation of surrounding rock of roadway under coal pillar in close distance coal seams.Therefore,the roadway repair technology composing of grouting reinforced and high strength bolt support for broken surrounding rocks was proposed.The project practice showed that the integrity and anchoring ability of roadway surrounding rocks was improved significantly and the anchorage zones and deep surrounding rocks were connected,so that the deformation of roadway surrounding rock was effectively controlled,and safety production of mine was guaranteed.