Quasi-static laboratory testing of a new rock bolt for energy-absorbing applications

• We introduce a newly developed rock bolt for energy-absorbing applications in details, including its layout and principle.
• Direct quasi-static pull tests were performed to examine the performance of the new bolt.
• Results show that it can elongate to any expected length at a high load level.
• A simplified method is proposed to calculate its loading capacity.

High stress in the surrounding rock mass can cause serious stability problems. The applied support system used under high in situ stress condition should be able to carry high loads and also to accommodate large deformation without experiencing serious damage. This paper presents a specifically designed rock bolt for energy-absorbing applications, which can provide support for squeezing and burst-prone rocks often encountered during underground excavation in the tunneling and mining community. The bolt mainly consists of a smooth steel bar with an anchor near the bottom end of its body. The anchor is firmly fixed within a borehole using either cement grout or resin, while the smooth section of the bolt inserted in the anchor can slide in response to rock deformation once the load exceeds the pre-set capability. Static pull tests on the new bolt show that it can elongate to any expected length at a high load level, thereby absorbing a large amount of energy to maintain the stability of surrounding rock.