Experimental Investigation on Rockbolt Performance Under the Tension Load

Abstract

Rockbolt performance may vary differently under complex geological and stress conditions, especially dynamic disturbance at deep underground mining. Therefore, reinforcement mechanism needs to be further explored to improve the support effect of rockbolt. In this study, static and dynamic Brazilian splitting tests of steel bar reinforced red sandstones were carried out to investigate the rockbolt performance under tension load. The deformation changes on the specimen’s surface and the rockbolt were recorded during the test. The strengths and failure modes of unreinforced and reinforced Brazilian disc samples were investigated. The results show that the stress of bolt increases steadily during elastic deformation process, indicating that the bolt shares the tension loading, and increases sharply when the bear capacity of specimen descends caused by crack propagation, indicating that the load is transferred from sandstone specimen. Furthermore, most of the damaged reinforced samples were still bonded by rockbolt, when the test finished. Therefore, the reinforcement mechanism can be divided into two phases. The first phase is the intact rock stage, during which the bolt shares stress reinforcing the strength. The second phase is crack propagation stage, in which the bolt restricts the crack propagation and almost bears the load. Compared with the results of unreinforced samples, it can be seen that the bolt can reduce failure of rock and the strength of the reinforced samples is enhanced. The results may provide a reference for analysis of reinforced mechanism and design of rockbolts.