Basic Guide to Active Ground Support Techniques in Mining


Ground support utilizes different methods to preserve or mobilise the initial strength and stability of the rock mass in order to provide safety for mining operations. This will provide a stable environment for the excavations to go on and there are active and passive ground support techniques that can be used to achieve this function. There are also techniques that offer support and certain techniques that will be used for reinforcing the rock mass.

In support techniques, an external force is applied on the rock surface that has undergone deformation. Reinforcement is where additional internal support systems are used so that the rock mass can be improved in its integrity before the deformation starts to happen. There are professionals who are in the field who will decide which techniques are best for the situation at hand and which ground support equipment to go with. Active support techniques are where we take action in order to increase the existing strength and stability of the rock mass. But there are preventative actions we can take in order to avoid failure of the rock mass. These actions will be under passive support systems.

One of the active support systems that are commonly used is roof bolts. It is also called rock bolts. The rock mass will be drilled and a roof bolt will be inserted into this. When you rotate this roof bolt, the expansion shell will expand into the rock mass and it will lock the rock in place. The length of the bolt and its diameter will be chosen based on calculating the weight of the rock that the bolt will support. There will be several roof bolts used and these will increase the strength of the rock mass. The weak layers of the rock mass will be clamped by the bolt in order to create a strong beam. This is used in both underground and surface mines. There are certain situations where the rock mass is slightly less stable and prone to forming cracks. In this case, resin will be applied into the hole drilled into the rock mass and the resin will fill the hole when the bolt is being tightened.

Cable bolts are used when longer bolts than a roof bolt are required. The anchor needs to be in a competent rock layer to complete its function. And when the competent rock layer is much further away, you will need to use cable bolts. The length of the cable bolt will depend on this and the difference in methods when it comes to roof bolts is that when you feed the cable to the drilled hole, concrete grout will be pumped in after it into the ground. Shotcrete can be used when pillars of rock are under a great amount of stress and in danger of failing. The outer layers of the pillars will start cracking and shotcrete can add to the strength of the pillar once it finishes curing after application. Shotcrete is a polymer or a cement mix that will have some fibres to improve the structural strength as well.