Investigating the Influence of Embedment Length on the Anchorage Force of Rock Bolts with Modified Pile Elements

The embedment length (EL) of full-grouting rock bolts is a core factor in rock bolt reinforcement. Therefore, understanding the influence of EL on the reinforcement performance of rock bolts benefits the rock reinforcement quality. To realise this purpose, this paper adopted the numerical modelling method. In this numerical modelling method, the structural elements of modified piles were used. The elastic debonding law was incorporated into the modified pile elements to model the debonding behaviour of the surface between rock bolts and grout. The results showed that the sliding of modified pile elements had a marginal influence on the reinforcement performance of rock bolts. Moreover, the EL has a paramount influence on the reinforcement performance of rock bolts. Before the rock bolts reached the largest anchorage force, there was a linear relation between the largest anchorage force and the EL. It was effective to use the linear regression analysis method to predict the critical EL of rock bolts. This finding was also applicable to fibre-reinforced polymer (FRP) rock bolts. Additionally, the rock bolt type had a paramount influence on the reinforcement performance of rock bolts. Before the rock bolts reached the largest anchorage force, metal rock bolts showed much larger initial stiffness than FRP rock bolts.

Automated summary

The embedment length (EL) of full-grouting rock bolts is crucial to their reinforcement performance. This paper used numerical modeling to investigate the influence of EL on reinforcement and found that EL has a significant impact. A linear relationship between the largest anchorage force and EL was observed, allowing for the prediction of critical EL using linear regression analysis. The study also revealed that the type of rock bolt is important, as metal rock bolts showed greater initial stiffness than FRP rock bolts.