Rock Support and Bolting Systems
Expandable Friction Bolts
Folded steel tubes inflated with high-pressure water so they grip along the full hole length. Immediate load capacity with no cure time, which suits development advance.
Features
- Inflation with high-pressure water expands the tube against the hole wall, generating friction along the whole bolt length.
- Load capacity is available immediately on installation, so the face can be advanced without waiting for a cure.
- Frictional grip along the full length means the bolt keeps working even if the rock moves and cracks locally.
- Hole diameter tolerance is tight, because an oversized hole prevents the tube reaching full contact pressure.
- Galvanised and coated versions are used where ground water would attack a bare tube within the design life.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Bolt length | 1,5 - 6,0 | m | Set by the depth of the zone being supported. |
| Rated load capacity | 100 - 240 | kN | Has to meet the design capacity for the pattern. |
| Required hole diameter | 32 - 52 | mm | Oversized holes lose capacity; tolerance is tight. |
| Corrosion protection | bare / galvanised / coated | Selected from ground water chemistry and service life. |