Performance of a fully grouted GFRP rock bolt under combined pull and shear loading

Abstract

Glass Fiber Reinforced Polymer (GFRP) rock bolts is gaining attention, as an alternative to steel bolts, for permanent rock support in civil underground infrastructures like road tunnels. GFRP holds many advantages for this purpose, including light weight, lower environmental impact and excellent durability characteristics. However, the shear strength of GFRP rock bolts has been a concern, particularly in a combined loading condition. The paper presents an experimental study that aims to evaluate the performance of a GFRP rock bolt subjected to combined pull and shear loads. It was found through laboratory tests that the strength of the rock bolt at a 47o displacement angle was similar to the tensile strength of the bolt (0o ), while in the range of 47o to 72o the strength would drop to a value closer to what was measured in pure shear (90o ). Finally, a numerical model has been established, to replicate the obtained results. the modelling can reasonably capture the performance of the bolt in a pure pull scenario, but it is not able to predict the behaviour in shear.