AU5935698A - Yielding adapter for rock bolts - Google Patents

Description

TRUE COPY

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION STANDARD PATENT YIELDING ADAPTER FOR ROCK BOLTS The following statement is a full description of this invention, including the best method of performing it known to me: u.

00 *000 00 0*0* 0* 0 0 e M M YIELDING ADAPTER FOR ROCK/CABLE BOLT This invention relates to an adapter than can be installed on cable bolts and most point anchor bolts to allow the bolts to yield when under extreme load often in the event of seismic activity.

YIELDING ADAPTER comprises a cylinder with a cone inside. The cone is slightly larger than the diameter of the inside of the tube.

When the Adapter is used with a Cable Bolt the cylinder is installed at the end of the hole and the hole is filled with grout making the adapter a point anchor for the cable bolt.

The Cable Bolt would pass through the cylinder and cone and be clamped. The Clamp must fit against the cone and be strong enough to bear the breaking strain of the cable. Alternatively the cone itself could incorporate a clamp.

The Cable Bolt on installation will be installed inside a plastic or poly tube to stop the grout from adhering to the cable. Alternatively the cable could be covered with oil or grease to obtain the same effect.

The breather tube for the grouting cycle will be taped to the Cable Bolt.

This will keep the Yielding Adapter in place until the grouting cycle is finished.

Once the cable is grouted and the specified time is allowed for the grout to set a bearing plate and clamp is installed at the end of the cable. On completion this will allow the Cable Bolt to yield the distance of the cylinder and the tonnes of yield determined by the thickness of the walls of the cylinder and the size of the cone.

2 The Yielding Adapter cylinder will be constructed of mild steel or a similar type material and be hollow inside leaving a wall thickness depending on what load is required before it deforms and allowed the cone to yield.

The Cone will have a hole in it for the bolt to pass through and the taper on the cone will start slightly smaller than the inside diameter of the cylinder and increases.

The ratio of the tube thickness and cone size will dictate the tonnes of load required to allow the cone to yield inside the cylinder.

The cone will be placed inside the cylinder before installation. It is :....envisaged that the material used for the cone will be harder than that of the cylinder, and expansion grooves or slots could be provided in the cone to allow any build up of material to escape.

The base of the cylinder will have to be thick enough to take the full 00 breaking strain of the bolt.

o When the predetermined load is reached the cone is pulled further into the cylinder expanding the walls as it is drawn down allowing the bolt to yield. When the cone reaches the base of the cylinder the Bolt will pull the cylinder into the grout until bolt failure.

0 00o YIELDING ADAPTER FOR CABLE BOLTS (Drawing No 1 Page 1/2) 1. Clamp on Cable Bolt 2. Cone 3. Walls of Cylinder 4. Cable Bolt 5. Base of Cylinder Grout in Hole 7. Covering over Cable Bolt to stop grout from adhering to Cable 8. Bearing Plate 9. Clamp on Cable *o o* YIELDING ADAPTER FOR POINT ANCHOR ROCK BOLTS (Drawing No 2 Page 2/2) 1. Resin used for anchoring bolt 2. Rock Bolt 3. Bearing Plate 4. Base of the Adapter 5. Side walls of the cylinder 6. Cone 7. Nut on Rock Bolt 9 **oo*

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Applicant: DMHS Resources Pty Ltd A.C.N. 081 990 481 Henry Alexander Stirlincy Director 17 March 1998

DMHS

RESOURCES

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