Study on surrounding rock fragmentation mechanism and reinforcement technology of mining roadway in the lower group of close coal seam

In order to solve the problems of surrounding rock fragmentation and support failure in the mining roadway in the lower group of close coal seam, based on the engineering background of Shaping coal mine, the stress distribution law of the lower floor strata in the goaf of the upper group coal seam and the deformation and failure characteristics of the lower group coal roadway are analyzed by the method of combining numerical simulation and theoretical analysis.The combined control technology of full-face grouting in deep and shallow hole level and bolt supporting has been successfully applied in engineering practice.The engineering practice results show that the combined control technology of deep and shallow hole grouting and bolt has realized the omni-directional reinforcement of the mining roadway in the lower group of close coal seam.The cumulative deformation of roof in the test area is about 50 mm, and the cumulative deformation of both sides is about 140 mm.The surrounding rock structure of the roadway is relatively complete and there is no loosening damage.It effectively solves the broken surrounding rock roadway in the lower group of close coal seam support problems.