Variation in load transfer along the length of fully encapsulated rock bolts, based on the installation mixing parameters

The reinforcement quality of the fully resin encapsulated bolt depends on several factors, which are a combination of the bolt design configuration, bolt/hole diameter ratio and installation procedure. Gloving in bolt installation constitutes a challenging problem for effective strata reinforcement and the stability of gate roads and tunnels. A total of ten bolts were installed into ten 1.7 m long threaded steel pipes with different resin spin times, the pipes were retrieved from the installed holes in an underground mine road way roof and then cut into 100 mm long sections. The encapsulated bolts in the tube sections were then push tested. Significant variations were found in bond strength along the installed bolt length in the whole tube, with typically the top 200 mm of bolt being significantly lower (50%) in most cases due to gloving and unmixed resin components.