Rock Bolts are generally formed from solid threadbar systems, i.e. bar, nut, couplers and plates. The steel threadbar is used to bond unstable rock to stable sections, beyond the face, and requires both capacity for tensile and shear loads. Rock bolts are fully bonded and unlike ground anchors are passive installations.
Unless it has been severely weathered, rock will usually allow for an open hole to be drilled without any risk of collapse. Solid threadbars offer the most efficient means of transferring load and maintaining the smallest diameter borehole. Due to the higher bond strength offered by rock compared to soil, rock bolts can be installed into a much smaller hole than soil nails or ground anchors.
Smaller boreholes are desirable, as drilling through rock can be time consuming and expensive.
Fully threaded bar - can be cut and coupled at any point. They have a robust threadform that makes them ideal for construction site use:
- Coarse Pitch Threadform (d/2, except Ø 63.5mm which is d/3) with two flats – ensures thread is self cleaning
- Fully Galvanized Systems – galvanized threadbars and accessories also readily available