Bolting with pumpable reactive resins - More than fixation of steel dowels in rock

Rock bolting in tunnelling and mining has been used for more than 100 years. The mechanism of how anchors behave, application and patterns have evolved into standard practices for all types of underground excavation. Passive acting bolts and dowels, as well as the active pre-tensioned bolts act in a way to limit shear and are subject to tension, which nails the rock mass together. Injection is used in underground structures to manage water ingress and less often to reinforce the rock mass systematically. Typically, the injected cementitious material fills the cracks and fissures in the rock mass and increases the shear resistance within the treated area. The use of pumpable, thixotropic, water insensitive, fast reacting resins to encapsulate rock bolts potentially offers to combine the nailing and shear resisting effect of the bolts with an injection approach. When using an accurately controlled pressure and volume regime, the rock mass can be bonded together, resulting in a significant improvement of the overall rock mass properties. A new rock bolt anchoring resin has been developed to improve the efficiency of underground support combining the positive effects of rock bolting and injections as outlined above. The driving idea behind this concept and test results are discussed in this paper.