Parallel computation method for critical stress of roadway with a combination of bolts and a simplified hydraulic support

The critical stress is a foundation for evaluating the safety of roadways in rockburst coal mines. Currently, theoretical formulas are widely used to estimate the critical stress, possessing limited applicability. The self-developed StrataKing (a GPU parallel computing system for strata movement), undergoing development over a decade, demonstrates high efficiency, high precision, large-scale computational capability, and apparent mining features, and has been combined with the disturbance response instability theory of rockbursts to investigate the critical stress-impact energy index relation of the circular roadway under hydrostatic pressure and without supports, exhibiting a great potential of high-performance computing in rockbursts. Numerical results of the critical stress of the roadway with a combination of bolts and a hydraulic support were obtained by use of StrataKing, in which the bolt is allowed to break and the hydraulic support is allowed to crack. Firstly, the mechanical behaviors of the tensile bolt and the hydraulic support were modeled to validate the correctness of the numerical method for supporting components. Then, for an actual case, the critical stress of the roadway with a combination of bolts and a hydraulic support was calculated, and evolution of the roof subsidence and displacements at two sides were monitored. For comparison, the critical stresses of roadways with bolts and without were also calculated. Finally, to demonstrate the correctness and advantages of the proposed method, the results obtained in this study were compared with the theoretical critical stresses based on the disturbance response instability theory of rockbursts. Results show that the critical stress is highest for the roadway with a combination of bolts and a hydraulic support, which is more effective for prevention of rockbursts. A combination of the bolts and a hydraulic support provides a better protective effect for the roadway roof, not for two sides of the roadway. The critical stress calculated by use of StrataKing for the roadway with a combination of bolts and a hydraulic support is significantly higher than the theoretical result without correction, higher than the theoretical result corrected by a fitted curve-based modification coefficient, but lower than the theoretical result corrected by the maximum modification coefficient. Compared with the theoretical calculation, the numerical simulation of the critical stress is more suitable for actual complex cases. Thus, prevention of rockbursts is more scientific. StrataKing can provide a powerful computing power support for the safe assessment of roadways in rockburst coal mines, helpful for the digital transformation and high-quality development of the coal industry.