Heat Treated Thread Deformed Bar - Rock Bolt Parts
Heat treated threaded deformed rock bolt is composed of following parts: 1 Bar; 2 Nut; 3 Nylon Washer; 4 Dome Washer; 5 Plate;
L: Length of Bar; l Length of Threaded Portion; m Diameter of Bar
Anchoring Ways of Rock Bolt
There are 3 major ways of anchoring the rock bolts: mechanical, grouted, and friction. The most common form of mechanically anchored rock bolt uses an expansion shell. A wedge attached to the bolt shank is pulled into a conical expansion shell as the bolt is rotated. This forces the shell to expand against the wall of the borehole. The two mechanisms by which the shell is anchored against the borehole wall are friction and interlock. A preload can be applied to the rock surface by tensioning the bolt with an attached hanger or face plate, which are designed to distribute the load uniformly onto the surrounding rock.
There are 3 major ways of anchoring the rock bolts: mechanical, grouted, and friction. The most common form of mechanically anchored rock bolt uses an expansion shell. A wedge attached to the bolt shank is pulled into a conical expansion shell as the bolt is rotated. This forces the shell to expand against the wall of the borehole. The two mechanisms by which the shell is anchored against the borehole wall are friction and interlock. A preload can be applied to the rock surface by tensioning the bolt with an attached hanger or face plate, which are designed to distribute the load uniformly onto the surrounding rock.
Rock Bolt Safety Certificates
Rock Bolt for Roof Bolting Support
The main function of rock bolt is roof bolting, which is to bind stratified or broken rock layers together to prevent roof falls. In order to achieve this purpose 4 basic theories have been established for roof bolting：
- Simple skin support;
- Suspension of a thin roof layer from a massive bed;
- Beam building of laminated strata;
- Keying of highly fractured and blocky rock mass.
Mechenical Properties of Threaded Deformed Rock Bolt
| Steel Grade | Yield Strength | Tensile Strength | Elongation After Fracture | Elongation under Max Force | Impact Absorb Energy | |
| Rel/MPa | Rm/MPa | A/% | Agt/% | kv2/J | ||
| NOT LESS THAN | ||||||
| Industrial Standard | MG335/MG400 | 335 | 500 | 15 | 40 | |
| MG500 | 500 | 700 | 22 | 100 | ||
| Our company Standard | 600 | 600 | 750 | 19 | 9 | 90 |
| 700 | 700 | 850 | 17 | 7.5 | 80 | |
| 785 | 785 | 930 | 16 | 5.5 | 60 | |
| 830 | 830 | 1030 | 15 | 4.5 | 50 | |
Available Dimensions of Threaded Deformed Rock Bolt
| Suface Type | Nominal Diameter Dn/mm | Nominal Cross SectionSn/m㎡ | Weight per meter g/m | Top strength level MPa |
| Levorotation, no longitudinal rib | 16 | 201.06 | 1578 | 800 |
| Levorotation, no longitudinal rib | 18 | 254.47 | 1998 | 800/1080 |
| Levorotation, no longitudinal rib | 20 | 314.16 | 2466 | 800 |
| Levorotation, no longitudinal rib | 22 | 380.13 | 2984 | 800 |
| Levorotation, no longitudinal rib | 25 | 490.88 | 3853 | 800/1080 |
| Levorotation, no longitudinal rib | 28 | 615.75 | 4834 | 800 |
| Levorotation, no longitudinal rib | 32 | 804.25 | 6313 | 800/1080 |
Production Process Compare of High and Medium Tensile Rock Bolt:
| Rock Bolt Tensile Strength | Production Process |
| 335MPa ~ 500MPa (Medium) | Raw Material — Reduce diameter — Screw thread — Test — Packaging — Stock |
| 600MPa ~ 700MPa (High) | Raw material — Heat Treatment — Mechanical Property Test — Sawing/Cutting — Reduce diameter — Screw thread — Test — Packaging — Stock |
Application of Threaded Deformed Rock Bolt :
High Tensile Strength Rock Bolts are applicated in structure and construction projects as follows:
- Coal mining
- Hard rock mining
- Civil construction
- General construction
- Geotechnical and Shoreline
- Bridges
- Dams
- Infrastructure
- Tunnels
