Rock Bolt & Ground Support Installation
Application Overview
Underground rock bolt installation is the backbone of ground support in mining and tunneling. Every heading, decline, stope, and tunnel relies on rock bolts to stabilise the rock mass and protect workers. The drill bit determines hole quality, which directly determines bolt capacity and ground support effectiveness. A worn or incorrectly-sized bit means reduced bolt pull-out resistance and compromised safety. Zhonghuan supplies the SDS-Max drill bits and chisels that mining supply companies and ground support contractors need, factory-direct with OEM flexibility.
Recommended Products
| Product | Size Range | Rock Bolting Application |
|---|---|---|
| SDS-Max Hammer Drill Bits | 16-40 mm x 500-920 mm | Rock bolt holes for split sets, resin bolts, expansion shell bolts |
| Pointed Chisels | SDS-Max, 400-600 mm | Scaling loose rock and overbreak before bolt installation |
| Flat Chisels | SDS-Max, 400-600 mm | Trimming bolt collar areas for plate seating |
| Bushing Bits | SDS-Max | Roughening shotcrete surface around bolt plates for re-spray adhesion |
Application Scenarios
1. Split Set Friction Bolt Installation
Rock Type: Medium-hard rock (sandstone, limestone, moderate-strength ore bodies)
Recommended: SDS-Max, 33 mm x 600-800 mm (for 39 mm split sets) or 38 mm x 600-800 mm (for 47 mm split sets)
Notes: Hole diameter is critical for split set performance -- an oversized hole reduces friction grip and bolt capacity by up to 50%. Replace bits as soon as gauge wear is visible. Drill depth should equal bolt length minus 30-50 mm to leave the ring exposed for washer and plate seating. In fractured ground, reduce percussive force to prevent hole collapse around the bit.
2. Resin-Grouted Rock Bolt Installation
Rock Type: Varies -- from soft shale to hard granite
Recommended: SDS-Max, 27-28 mm x 500-920 mm (for 20 mm rebar bolts), or 33 mm for 25 mm rebar
Notes: Hole diameter must allow the resin cartridge to be inserted and then mixed by spinning the bolt bar. The annulus (gap between bar and hole wall) must be 3-4 mm on each side for proper resin flow. Blow the hole clean of cuttings before inserting resin cartridges -- cuttings dilute the resin and reduce bond strength. In up-holes, resin viscosity must be high enough to prevent drainage before setting.
3. Pre-Bolting: Scaling and Surface Preparation
Application: Removing loose rock wedges and slabs before systematic bolting
Recommended: SDS-Max pointed chisel for scaling, flat chisel for plate seating areas
Notes: Scaling must be done before every bolting round to identify and remove loose blocks that could fall during or after bolt installation. Pointed chisels pry out loose wedges along discontinuity planes. Flat chisels prepare a level surface for bolt plates to seat properly -- a plate that does not sit flush cannot transfer load and the bolt becomes ineffective. Use bushing bits to roughen old shotcrete where new spray coats are needed around bolt collars.
Selection Tips
- Match bit to bolt type exactly: Split set = hole smaller than bolt OD. Resin = hole larger than bar for resin annulus. Expansion shell = hole matches shell OD. Check the bolt datasheet.
- Select carbide grade for rock hardness: Standard carbide for soft-medium rock (under 120 MPa UCS). Premium carbide for hard-very hard rock (above 120 MPa). Premium tips cost 20-30% more but last 30-50% longer in hard rock.
- Choose bit length by bolt length: Bit must be at least 50 mm longer than bolt embedment depth. Common lengths: 500 mm (short bolts), 600-800 mm (standard 2.4 m bolts), 920 mm (3 m bolts).
- Monitor gauge wear: Replace bits when diameter undersize exceeds 0.5 mm. Worn bits drill undersized holes that reduce split set grip and prevent resin cartridge insertion.
Ordering Information
- ISO 9001 Certified -- documentation supplied with every shipment
- MOQ: Reviewed case-by-case based on product scope and packaging
- Bulk Mining Packs: High-volume cartons for underground consumable stores
- Private Label: Laser etching + custom packaging available
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