Rock Bolts – Solid Bar
| Physical Properties | Minimum | Typical |
|---|---|---|
| Yield Strength | 540MPa / 160kN | 615MPa / 185kN |
| Tensile Strength | 660MPa / 195kN | 725MPa / 215kN |
| Calculated Shear Strength | 120kN | 130kN |
| Standard Elongation | 16% | 19% |
| Uniform Elongation | - | 12% |
| Mass Per Metre | - | 2.47kg |
| Bar Diameter | - | 20.0mm |
| Cross Sectional Area of Bar | - | 300mm2 |
| Major Bar Diameter | - | 22.1mm max. |
Key Features
- The 20mm debonded Posimix bolt system is designed to allow for a specified amount of ground deformation according to the rock mass demand requirements.
- The system is fully resin encapsulated with various debonded lengths available on the bolt for particular mining situations. The debonded region of the bolt means the majority of the energy is dissipated by deformation of the bolt within this region.
- The debonded Posimix section is provided in lengths of 1m -1.4m for most practical mining applications.
- Extensive dynamic testing has been completed by the WA School of Mines.
- The Posimix bolting system was designed to assist in the installation of rock bolts with chemical anchors in larger diameter holes (35-38mm) by providing:
- substantially enhanced mixing of the chemical anchors
- increased load transfer capabilities
- ability to be installed with a face jumbo as well as hand held machines.
- The Posimix device centralises the bolt in the hole allowing an even distribution of the chemical anchor around the bolt. It also acts as an Archimedes screw pump forcing the chemical towards the back of the hole, assisting in mixing whilst consolidating the anchor for improved load transfer properties.
- Recommended hole size is 35-38mm in diameter
- Corrosion protection alternatives to hot dip galvanizing may be provided
Dynamic load-displacement response on various decoupled Posimix configurations
Energy dissipation – Posimix bolts
| Sample Number | Bolt Length (mm) | Debonded Length (mm) | Deformation at discontinuity (mm) | Energy dissipated (kJ) | Test Result | Demand category application |
|---|---|---|---|---|---|---|
| 173 | 2400 | 0 | 35 | 7 | Rupture | Low |
| 172 | 2400 | 1000 | 115 | 26 | Rupture | Medium |
| 176 | 2400 | 1000 | 96 | 21 | Stable | Medium |
| 177 | 2400 | 1000 | 77 | 27 | Rupture | Medium |
| 208 | 2400 | 1400 | 171 | 42 | Stable | High |
| 209 | 2400 | 1400 | 113 | 29 | Stable | High |
| 210 | 2400 | 1400 | 128 | 33 | Stable | High |
Installation Guide Lines
- The rock bolt hole is drilled as per mine support designs.
- Hole depth is critical. Hole depth should be shorter than the bolt to allow for the height of the washer and nut.
- After insertion of the resin anchors the bolt is rotated through the anchors while being pushed to the back of the hole.
- In the case of full encapsulation, anchors of different setting times are often used and the higher speed anchor is to be inserted first followed by the slower speed anchors.
- It is important to follow the resin anchor recommended mixing and hold times as printed on the resin anchor cartons. DO NOT OVER MIX.
Standard Lengths & Packaging
- Standard bolt lengths range from 1500 to 3000mm in 300mm increments.
- Non-standard lengths are available by negotiation.
- Bolts are packaged in bundles with threads protected by heavy duty polyethylene bags.
- Bolt fittings, such as nuts, anti-friction washers and dome balls, are supplied fitted to rock bolts in the configuration requested.
Notes
- Only DSI rock bolt components should be used to enable the optimum performance of the bolt system to be obtained.
- Assistance should be sort from DSI Technical Services Engineer’s in selection of the correct Posimix bolt for the application together with its product code.
- DSI Underground Mining Products Division is Quality Assured to ISO 9001:2015, Registration QMS 41328.
