Investigating the mechanical behavior and failure mechanisms of rock bolts subjected to multiple impact loads using a newly developed experimental test apparatus

Abstract

Understanding the behavior and failure mechanisms of rock bolts subjected to multiple impact loads is essential for improving the safety and performance of underground support systems. In this study, a series of experimental tests were performed to investigate the deformation, energy absorption, and failure mechanisms of pre-tensioned rock bolts under multiple impacts. The result indicates that with an increasing number of impacts, the rebound amount of rock bolts gradually increases, while the plastic deformation decreases. The energy absorbing ratio of the rock bolt decreases as the energy releasing ratio increases, leading to a decline in the rock bolt’s ability to absorb energy and an increase in brittleness. It was observed that the accumulation of plastic deformation consumes the yielding and strengthening stages of the rock bolt, making it prone to fracture at smaller deformations in later stages. It was also found that the final elongation of a rock bolt subjected to multiple impacts leading to fracture is significantly higher compared to a rock bolt subjected to a pure pull-out test. These insights have important implications for the design of rock bolt support systems in underground excavations.