Mechanically anchored rockbolts or expansion shell anchors can immediately take effect once installed and are a simple means of rock reinforcement. The application of torque to the head of the bolt pre-tensions the bolt against the borehole. The shell has various designations to suit in situ conditions. Expansion shell anchors could be split into several categories: standard type, bail type and parallel expansion, as shown in Figure 1 (Minova, 2006). Due to their inherent nature, mechanically anchored bolts can only be used in fairly hard rock. The correct degree of torque must be guaranteed to make the bolts work effectively. Vibration of the surrounding rock mass can lead to the loss of bearing capacity.