Experimental investigation of the dynamic response of prestressed rockbolt by using an SHPB-based rockbolt test system

Abstract

A new rockbolt test system was developed to investigate the dynamic response of prestressed rockbolts. The test system involved the modification of a split Hopkinson pressure bar, such that the static prestress and dynamic tensile stress wave could be simultaneously applied on the rockbolt specimen. Strain gauges were mounted to the threaded bolt to trace the stress wave propagation in the rockbolt. Prestressed rockbolt specimens with various prestress levels were subjected to repeated impact loading. The effects of the prestress and number of impacts on the dynamic response of the rockbolt were investigated. The results indicated that with increase in the prestress, the resistance of the prestressed rockbolt to the dynamic impact is enhanced, and the slippage of the bolt decreases. Under repeated impacts, the slippage of the rockbolt increases exponentially with increase in the number of times that impact occurs. Finally, the failure mechanism of the prestressed rockbolt subjected to the dynamic impact was clarified.