In underground mining work, one of the biggest dangers is landslides. To protect workers, the industry has developed fortification processes. This technique consists of reinforcing the environment (walls and ceiling) of an excavation. To do this, they use support elements such as large bolts, meshes, frames, shotcrete, or a combination of them.
A fortification work carried out correctly becomes an excellent contribution to the safety of the mine. There are two types of fortifications. First, there are the rigid ones. They hold without allowing any movement of the rock. They must be strong enough to prevent the blocks from falling. You can use this type of fortification in those excavations where the rock is of poor quality or weak because of a previous process, like an explosion.
In second place are the flexible fortifications. These allow deformations in the rock, allowing the efforts to be relieved and when deforming, it improves the resistant properties. These works are carried out in chimneys, galleries, subsidence, and material collection sites, among others.
The Large Bolts in the Mines’ Fortification
There are different types of anchor bolts in the industry, which vary slightly in their design, but which fulfill the same function. According to the technique used to fix them, you can classify it into mechanically anchored bolts, rod bolts attached with cement or resin, and bolts anchored by friction.
Mechanical Anchor Bolt
It consists of a steel alloy rod, which has a mechanical expansion anchor at one end. The other end may have a forged or threaded head, where a metal base plate goes. When using the threaded bolts, you finish the anchor with a nut, which is tightened to press the rock. The metal plates can be flat or concave, according to the installation needs.
The reinforcement action occurs immediately after installation. This type of anchoring is right for moderately hard, hard rocks, massive rock, with blocks or stratified, without the presence of water.
Rod Bolts Attached with Cement or Resin
It is an iron or steel alloy rod with a beveled end, fixed on the inside with cement, resin or a combination of both. With this technique, you obtain three types of anchoring: chemical adhesion, friction, and fixation.
You can use this type of anchor can as temporary or permanent reinforcement. It is the best system for rocks in high-stress systems or rocks of inferior quality. You obtain the full fortification once the cement or resin has completely dried.
Bolts Anchored by Friction
This system is the most recent. There are two types: Split Set and Swellex. In both cases, the anchoring factor is the fixation between the bolt and the rock. The Split Set is a strict friction system, while the Swellex also combines an expansion mechanism at the inner end. In short-term anchors the presence of water is irrelevant, but it is not suitable to use them permanently in these conditions.
Dyson Corp serves a large number of underground and surface mining processes. We provide custom solutions according to your needs to complete all your earth-shattering mining projects. Contact us; we will gladly assist you in your project.