Self-Drilling and Hollow-Core-Rock-Bolts

Self-Drilling and Hollow-Core-Rock-Bolts

The main feature of the standard self-drilling anchor (sda) system is the use of a single drill bit in combination with the anchor as drilling steel. Therefore, the rock bolt is connected to the hydraulic rock drill via an adapter device and installed in a traditional way.

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Product Description

Self-Drilling Anchors (SDAs) are hollow core rockbolts which serve as both the drill string during drilling of a support hole, and as the support tendon once grouted into place. A single use drill bit, selected tosuit the ground condition, is fitted to the leading end of the SDA with a plate and nut ftted on the trailingend. Couplers can be used to combine SDA sections for extension bolting。

Hollow core bolts (HC Bolts) utilise the same hollow bar as SDAs but are supplied without a drill bit for applications where a convetional drill string can be used to drill the support hole. Once the HC Bolt isinserted into the pre-driled support hole, resin or grout is injected through the bolt to complete the installation.

Composition

Sacrificial dril bita fully threaded hollow steel bar,

A coupler to continue the hollow steel bar if necessary,

A plate and a nut to transmit the force from rock mass,

A centralizer to ensure the hollow steel bar being at the central positon of the drilling hole,

An alternative shank is required if the drilling rig has the percussion function.

Installation

1. Do some checking, including if the drilling rig works, whether anchor body is unblocked, and so on.

Select a proper drill bit according to the following factors: service life, maximum length of anchor body, geological condition, geometry.

2. Connect the grouting pipe with the rotary grouting adapter and open the grouting machine, it will automatically simultaneously grout when drilling.

This is the feature of self drilling anchor rock bolt differing from other traditional solid anchor bar. It is no risk of hole collapsing when drilling in the unstable rock and soil mass.

3. With the coupler, it is possible to extend the anchor body to meet the required drilling depth. All you need to do is just screwing the coupler on the end of an anchor body by your hand.

4. After the slurry curdles, install the plate and nut.

Advantages

1. It features a hollow bore for flushing, or simultaneous drilling and grouting.

2. Reliable, Efficient and Convenient.

3. Choice of drill bits for different ground conditions.

4. It can be elongated by using couplers.

5. Suitable for anchoring in broken geological condition and narrow space, which has achieved perfect effect.