The term rock support is the term widely used to describe the procedures and materials used to improve the stability and maintain the load bearing capacity of rock near to the boundaries of an underground excavation. A distinction is drawn between rock reinforcement or active support, where the supporting elements are an integral part of the reinforced rock mass, and rock support or passive support, where the supporting members are external to the rock and respond to inward movement of the rock surrounding the excavation.
A good example of active reinforcement is a pattern of un-tensioned grouted bolts which are tensioned as the rock deforms and which interact with the rock in much the same way as reinforcing steel does with concrete. Steel sets are an example of passive support since they external to the rock mass and can only respond to progressive inward movement of the loosened rock mass.
The primary objective of a support system is to mobilise and conserve the inherent strength of the rock mass so that it becomes self-supporting. Rock support generally combines the effects of reinforcement, by such elements as rock bolts and cables, and support, with shotcrete, mesh and steel sets which carry loads from individual rock blocks isolated by structural discontinuities or zones of loosened rock. If possible, the installation of rock support should be carried out as an integral part of the excavation cycle to enhance the self -supporting aspects of rock mass improvement.
Source: Hoek and Wood, Underground Support Systems, 1987
Normet’s rock reinforcement portfolio includes bolt the D-Bolt®, self-drilling anchors (SDA) as well as chemical rock reinforcement.
The D-Bolt®, the deformable bolt, represents a new generation in energy-absorbing rock bolting. It is specifically designed for efficient and reliable rock reinforcement in both squeezing and burst-prone strata conditions. The D-Bolt® may be installed in either cement or resin grouts, most often in a holistic rock support system that includes sprayed concrete and mesh.
Our complete range of SDA provides a solution for efficiently installing reinforcing bolts in unconsolidated or fractured ground, where it is difficult to keep boreholes intact long enough for traditional bolt installation.
Our TamPur 116 resin can also be used to “reinforce” or glue unconsolidated and fractured ground together, and thereby gain strength and help the rock support itself. The Tampur 116 is typically used in combination with SDAs or injection packers.
For more information on our rock reinforcement products, please see the products sections.