Corrosion is a physical alteration of a material from electrochemical reaction with its environment that often results in reduction of the mechanical properties of that material. Rock bolts are particularly susceptible to corrosion as they can be exposed in their working environment to ground water. Corrosion increases markedly in sulphide […]

The primary role of the bolt reinforcement is to minimise displacement of the existing fractures by providing confining stress to the fracture surfaces.  In some cases, rockbolts may minimise some residual fracture formation within the moving strata. Rockbolts installed across the bedded, jointed or fractured strata is capable of resisting axial […]

The load transfer concept is central to an understanding of the load transfer mechanism of rockbolts. The schematic mechanism of the load transfer is shown in Figure opposite. The efficiency of load transfer significantly influences the performance of the reinforcement system. Fundamentally the movement of the reinforced rock block initiates […]

The profile configuration of rockbolts is defined by the rib profile shape, and height, angle of wrap and spacing or distance between the ribs. Both bolt profile shape and profile spacing (rib spacing) have been found to influence the bonding capacity of the grouted rock bolt. The bolt surface profile […]

For highly fractured and blocky roof strata, the application of rockbolts can essentially improve the frictional resistance along rock joints, cracks and weak planes as shown in Figure opposite. The installation of rockbolts can prevent or minimize the slippage and separation of rock discontinuities. Bolt tension plays a vital role […]

When the competent strata is not within reach of ordinary roof bolts or does not exist, rockbolts can still be applied to bind thin and weak individual layers together to form a “beam”. The internal rockbolts through the weak layers can provide direct shear resistance to the horizontal movement that […]

When roadways are excavated in underground coal mines, the laminated immediate roof tends to detach from the main strata. Suspension theory assumes that the immediate roof of the excavation is weak whereas the upper layer is relatively stronger. In such situations, rockbolts hold the immediate roof to the self-supporting main […]

In coal mining, the surrounding strata is weakened and fractured around mine openings in underground mines due to the in situ stress redistribution. The main purpose of rockbolt reinforcement is to improve the internal load bearing strength of the rock mass to support itself (Bieniawski, 1984). Rockbolt performance is influenced by the […]