rockbolting

Rockbolting is a rock reinforcement technique used in mining, tunneling, and civil engineering to stabilize unstable rock masses. It involves drilling holes into the rock and inserting steel bolts that are anchored to the surrounding rock, providing tensile support and improving overall rock mass strength. The bolts work by developing friction along their length and, when bonded with grout or resin, by transferring load into the rock as a bonded anchor. Rockbolts are typically used in conjunction with other supports such as shotcrete and wire mesh to form an integrated system.

There are two main categories: mechanical rockbolts and grouted (bonded) bolts. Mechanical bolts rely on an expansion mechanism or mechanical fixings to grip the rock and are quicker to install but may offer less long‑term stiffness. Grouted bolts are anchored with cementitious grout or chemical resin, creating a stronger bond and greater long‑term stiffness. Within grouted bolts, fully bonded and partially bonded (resin-anchored) systems are common.

Installation generally involves drilling holes of appropriate diameter and depth, inserting the bolt, and activating the anchor. For resin-based systems, epoxy or polyurethane capsules are injected before bolt insertion and the grout cures to form a bonded bond. Pretensioning is often applied to develop clamping force, and the installation is followed by the application of compatible facing supports such as shotcrete or steel lattices.

Design and application depend on rock mass quality, such as RMR or GSI, water conditions, and the required level of support. Proper design, installation, and monitoring are essential for safety and effectiveness.