Fracture Characteristics of Thick-Roof Coal Roadway Subjected to Duplicated Shock Waves

Abstract

Rock burst is one of the most serious risks for underground coal mines, and the associated dynamic waves generally cause roof falls and large-scale shrinkage of the roadway. The roadway is often seriously damaged by duplicated rock bursts. Previous research on the propagation and attenuation of shock waves cannot explain well the failure mechanisms of the surrounding rock of the roadway under duplicated dynamic waves. To fill this research gap, this paper presents comprehensive research on the failure and fracturing process of roadways affected by repeated shock waves using field tests and numerical analysis. A numerical model as per UDEC Trigon logic was developed and calibrated using mine earthquake shock waves, during which a user-defined FISH function was adopted to document the quantity characteristics of fractures (i.e., shear-slip and tension). The damage to the roof was assessed based on the quantity of fractures. At the same time, the simulation analysed the evolution trend of the failure zone of the roadway roof and the fracture development area, which agreed well with the field tests. According to the spread and extension characteristics of fractures in the surrounding rock under repeated shock waves, new support materials and schemes were proposed and applied at the mine site. The results show that the scheme has controlled the deformation of the roadway effectively and satisfied the safety and efficiency requirements of the mine.