An innovative energy-absorbing rock bolt for ground support in squeezing and rock burst conditions

Rock Engineering 2009 - Rock Engineering in Difficult Conditions
Abstract Deep mines face serious squeezing problems in weak rocks, while more and more rock bursts occur in hard rocks when the mining gets deeper with time. Ground support systems have to provide a satisfactory containment to the fragmented rocks in deep mines. The concept of ductile, or energy-absorbing, ground support has been accepted by many practitioners of ground support. Energy-absorbing elements are necessary components in a ductile ground support system. An innovative rock bolt, called D-bolt, is an element of such type. The D-bolt is a smooth bar with a limited number of anchors arranged along its length. It is fully grouted in the borehole. The D-bolt is only bonded with the grout in the anchor positions, while the smooth sections between the anchors can freely deform when subjected to a tensile load. The smooth sections independently provide reinforcement functions to the rock. Failure of one section would not affect the reinforcement function of other sections of the bolt. Therefore, the D-bolt has a more reliable reinforcement effect than two-point anchored energy bolts. The D-bolt is characterised by its large load-bearing capacity and also large deformation capacity. Both laboratory and field tests have shown up the satisfactory performance of the bolt in absorbing deformation energy. The test results will be presented in the paper.
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