Friction Anchor Bolts Split Set Rock Bolt For Mine Support

Friction Anchor Bolts Split Set Rock Bolt

The rod body of a slotted anchor rod is formed by rolling high-strength, high-elasticity steel pipe or thin steel plate, with a longitudinal slit cut along its entire length.

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Working Principle of friction bolt/split set

When a slotted tube bolt is installed in a borehole slightly smaller than its diameter, three forces are applied to the surrounding rock: radial pressure exerted along the entire length of the bolt against the borehole wall, frictional resistance to prevent rock mass slippage, and the supporting force provided by the bolt's tray and backing plate. These three forces collectively enhance the stability of the surrounding rock.

Advantages of friction bolt/split set:

Slotted tube bolts feature simple operation and convenient use. In underground shotcrete support, they offer strong anchoring force, high tensile strength, and significant expansion force, integrating the entire roof into a unified structure.

Technical Features:

1. Manufactured from high-strength alloy steel strips

2. Simplest installation process

3. No grouting agent required

4. High friction between anchor and rock mass

5. Exceptional shear and tensile strength

6. Equipped with high-strength plates for uniform load distribution

7. Tunnel height exceeds anchor length

Technical Requirements for friction bolt/split set：

1. The surface of slotted pipe anchors shall be smooth, free from severe scratches or corrosion. Welds shall be free from cracks, porosity, or slag inclusions, and burn-through of the pipe wall is not permitted. The tray shall move freely along the anchor body. The offset between the retaining ring joint and the slotted opening should be 170°-190°.

2. The pull-out force of the retaining ring weld shall be ≥80 kN. The ultimate tensile strength of the rod body shall be >110 kN. The initial anchorage force shall be ≥25 kN/m. The load-bearing capacity of the tray shall be >65 kN.

Initial anchoring force: 3–7 tons

Tube ring pull-out load: 8–10 tons

Anchor rod tube tensile strength: 12–13 tons

Corrosion resistance exceeds A3 steel by 20–30%, ensuring long-term service life