Rock Support and Bolting Systems
Mechanical Anchor Bolts
Point-anchored bolts tensioned against a face plate by torque, with an expansion shell at the far end. The quickest temporary support to install where the rock will hold an anchor.
Features
- Load is carried at the expansion shell, so the anchoring horizon has to be competent rock, not broken ground.
- Tensioning by torque against a plate puts immediate active load into the rock surface.
- Installation needs only a torque wrench or a bolter, with no resin, grout or water pump at the face.
- They can be grouted afterwards to convert them to a permanent, fully encapsulated support.
- Torque and the resulting bolt tension have to be checked on a sample basis, because a loose bolt looks identical to a tight one.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Bolt diameter | 16 / 20 / 22 | mm | Sets capacity and the required hole diameter. |
| Bolt length | 1,2 - 3,6 | m | The anchor has to reach competent rock beyond the loose zone. |
| Required hole diameter | 32 - 38 | mm | The expansion shell will not set in an oversized hole. |