Mechanical behavior and failure mechanisms of rock bolts subjected to static-dynamic loads

This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal bursts. Employing a house-made load frame to simulate various failure scenarios, pretension-impact-pull tests on rock bolts were conducted to scrutinize their dynamic responses under varied static load conditions and their failure traits under combined loads. The experimental results denote that with increased impact energy, maximum and average impact loads on rock bolts escalate significantly under pretension, initiating plastic deformation beyond a certain threshold. Despite minor reductions in the yield load due to impact-induced damage, pretension aids in constraining post-impact deformation rate and fluctuation degree of rock bolts. Moreover, impact-induced plastic deformation causes internal microstructure dislocation, fortifying the stiffness of the rock bolt support system. The magnitude of this fortification is directly related to the plastic deformation induced by the impact. These findings provide crucial guidance for designing rock bolt support in coal mine roadway excavation, emphasizing the necessity to consider both static and dynamic loads for improved safety and efficiency.