Rockbolts have been used for a very long time when it comes to underground support for excavations. There are also different types of rockbolts for different requirements as well. These are generally steel rods that come with a chemical or a mechanical anchor in one end. There will be a faceplate that comes with a nut at the end of the rockbolt. After a rockbolt is placed, it will be tensioned.

Rockbolts are used for long term and short term applications. In long term applications where you require permanence, the space formed between the rock and the bolt is filled with cement or resin grout. Shotcrete can be used as well. The designers for mine civil IT GSE will specify the type of ground support that is required in a situation and they will ensure that safety standards are upheld. When rockbolts are inserted for short term applications, grouting is not done. But this will change when there is corrosive underground water present as it will present a threat to the stability provided by the rockbolt. Mechanically anchored rockbolts such as expansion shell rockbolt anchors have a tapered end like a cone. A hole will be drilled before the rockbolt is placed. If the drilled length is not sufficient, the bolt can easily become dislodged. You can increase the anchor force by tightening the bolt.

The expansion shell anchors do well when it comes to hard rock but their effectiveness reduces when used in soft rocks and rocks that are closely joined together. It is difficult for the shell anchor to maintain a strong grip in this case. In these conditions, resin cartridge anchors are used. The anchor is at one end of the rockbolt and the faceplate at the other end is used to distribute the load from the bolt to the face of the rock. You will not find rock that is at right angles to the bolt so most of the time, a tapered washer is used. There are different types of faceplates and washers that you can find depending on the condition of the rock surface.

The threads that you find on a rockbolt should be coarse and they should not be cut. Rolled threads are recommended. When the thread is fine other than coarse, it can be damaged easily. When the thread is cut, the bolt is weakened and has a higher chance of failing. Rolled threads can be expensive because of the cost taken for the manufacturing. Tensioning is more important when it comes to bolts that are expected to carry a high load. A common reason for rockbolt failure is the corrosion of the bolt. This can be avoided when you fit the gap between the rock and the bolt with grout. Traditionally, a grout tube is used for this. You can also use a hollow core bolt when it comes to permanent installations as it has a higher level of reliability when it comes to the grouting process.