Surrounding Rock Deformation Mechanism and Control Technology for the Roadway in the Fault-Disturbed Zone under Special-Shaped Coal Pillars

Abstract

In order to explore the impact of residual special-shaped coal pillars and fault disturbances on the lower layered roadway, this study takes the short-distance coal seam mining in Luwa Coal Mine as the engineering background to explore the surrounding rock deformation mechanism along the mining roadway in the fault-disturbed zone under special-shaped coal pillars, it presents the roadway surrounding rock control technology and it conducts on-site industrial test verification. The study shows that the abutment pressures on the floor of special-shaped coal pillars are distributed as “three peaks and two ridges”. The part beneath coal pillars is mainly disturbed by vertical stresses, while the part below the coal pillar edge is co-affected by vertical stresses and shearing stresses, generating a stress concentration coefficient ranging from 1.26 to 1.38 in the lower coal seam. According to the superposed effects of special-shaped coal pillars and fault disturbance on the mining roadway, the mining roadway is divided into the lower section of goaf, the section crossing the coal pillar edge, the lower section of coal pillars, and the section obliquely crossing the coal pillar edge. According to the above sections, the segmental control strategies of “improving stress distribution on surrounding rock + reinforcing support on special sections” are proposed. A joint control technology of large-diameter drilling hole pressure relief and special section anchor cable reinforcement support was adopted to carry out on-site industrial testing and monitoring. Overall, the convergence rate on the roadway surrounding rock is controlled within 5%, and the deformation of roadway surrounding rock is under effective control.

Study on Characteristics of Front Abutment Pressure and Rational Stop-Mining Coal Pillar Width in Large Height Working Face

“…Based on the limit equilibrium theory and engineering practice [29,30], when the main roadway has just been disturbed, the width of the SMCP is the sum of the excavation stress field range Lr of the main roadway and the range Lw of the FAP (Figure 3). The range of FAP includes the widths of the plastic zone x 1 and the elastic zone x 2 , which can be calculated using the following formulas [31,32].…”