Fully Threaded Rock Bolt

The rock bolt for tunneling and mining is installed to the designed length to secure any loose rock mass and prevent the shear displacement after excavation. The traditional rock bolt fabricated from deformed rebar is sharpened at the edge for easier insertion into borehole and threaded at the end for screwing with nut & dome plate for anchoring. Recently, the full threaded rebar with higher strength but without pullout loading loss in the threading section is preferred for application as rock bolt on site. In addition, it is cost effective because no extra machining is required afterwards.

Rock bolts are installed for two purposes. One is to provide pre-tension in fragile geology condition, and the other serves as a mortar bolt for passive loading. For the pre-tension purpose, immediate anchoring of rock bolt with the surrounding rock mass is necessary. There are three kinds of anchoring material to fulfill the pre-tension purpose within 2-3 hours at most which are liquid accelerator cartridge, two-component resin cartridge and mechanical expansion shell. (Detail descriptions please refer to Chapter Anchoring Material.)

The mortar rock bolt cannot reach its loading capacity until the early strength of the mortar gains. Thus, it is generally used in softer geology conditions. In some cases, the grout mortar’s compressive strength in early stage is required to reach 10Mpa in 24 hours.