Anchor cables (bolts) act as the main support system and play an important role in improving the rock burst resistance and stability of the roadway surrounding the rock. In this study, the dynamic response characteristics of the roadway surrounding the rock and the support system under different shock intensities were investigated. The following findings were obtained. The stress wave propagation process under dynamic shock was divided into a stress vibration initiation stage, a stress fluctuation stage, and a stress adjustment stage. In the stress vibration initiation stage, the surface mass of the roadway surrounding the rock started to vibrate, and the pretension of the anchor cables (bolts) was reduced; in the stress fluctuation stage, the failure of the roadway surrounding the rock intensified, and the anchor cables (bolts) were damaged to some extent; and in the stress adjustment stage, the roadway deformation of the surrounding rock and the axial forces of the anchor cables (bolts) tended to stabilize. As the dynamic shock intensity increased, the vibration velocity, displacement increment, and acceleration amplitude of the mass of the roadway surrounding the rock increased exponentially. The critical shock energy of the roadway surrounding the rock was 105 J, above which the damage to the rock was aggravated. The larger the pretension of the anchor cables (bolts) was and the higher the dynamic shock intensity was, the more severe the damage to the anchor cables (bolts) was. Given the dynamic response characteristics of the roadway surrounding the rock and support elements under shock, a full anchor cable yielding support technology is proposed to effectively control the stability of the roadway surrounding the rock under dynamic shock, providing a reference for the construction of the support systems for preventing rock bursts in similar roadways.
Mining activities are key triggers for strong mine earthquakes and even rock bursts in coal mines. This study explores the impact of mining speed on the overlying strata’s deformation and energy release through theoretical analysis, numerical simulation, and the digital speckle method. The temporal and spatial evolution characteristics of the impact energy during mining are simulated. The digital speckle method illustrates a positive correlation between rapid mining and increased fracture block degree of overburden rock and roof separation, confirming that accelerated mining speed extends the fracture distance of the stope. Furthermore, numerical simulations establish that both the energy associated with overlying rock breaking and the frequency of energy occurrence events are amplified during rapid mining, in contrast to slow mining. This observation corroborates that escalating mining speed augments the energy dispensed by the breaking of the upper rock. Consequently, this escalation induces a transformation in the energy levels of mine earthquakes, culminating in a heightened incidence of large-energy mine earthquakes.
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.
Rock bursts have become one of the worst disasters in deep mines, and the safety of roadways is affected by stress waves generated when hard roofs fracture. Pictures of a mine site were collected using the Hujiahe mine as a case study. The damage characteristics of the roadway were analyzed and the damage process was reproduced using numerical simulation software. The attenuation characteristics of the strength of the shock wave as it passes from the impact shock source to the roadway are summarized. Based on the stress wave transmission mechanism and geological characteristics, a “shock wave attenuation model through rock formations“ was established to analyze the transmission characteristics of impact stress under the composite roof structure. The strength criterion and energy balance equation for roadway damage under the action of shock waves are derived. This work provides a reference for roadway support under similar conditions and can be generalized and applied elsewhere.
Deep longwall mining under large dip and advance inclinations can induce strongly asymmetric roof deformation and nonuniform load transfer, complicating the assessment of hydraulic support loading. Taking the 2902 working face of Chensilou Coal Mine as an engineering case, this study combines field monitoring, theoretical analysis, and FLAC3D simulation to investigate a recurrent M-shaped pressure distribution under a fixed geometry with dip and advance-direction inclinations of approximately 35°. Representative field profiles at cumulative advance distances of 40, 60, 80, and 100 m consistently exhibited an M-shaped hydraulic support pressure distribution. To interpret this spatial pattern, the main roof was represented as a bidirectionally inclined equivalent elastic plate with three clamped edges and one free edge, while the hydraulic support–immediate roof system was represented by a local Winkler foundation. The analytical solution identified two spatially separated roof-deflection concentration zones, and the FLAC3D results exhibited a broadly similar bimodal pressure tendency. The complete 28-day monitoring record was subsequently analyzed to examine whether the observed pattern persisted beyond the four representative advance stages, revealing two recurrent high-pressure sectors approximately within supports 45–75 and 105–135. The field, analytical, and numerical results showed approximate sector-level correspondence. This study therefore provides a case-specific mechanical framework relating recurrent zonal hydraulic support loading to spatially variable overburden loading, asymmetric equivalent boundary constraints, nonuniform main-roof flexure, and local roof–support load transfer.