ABSTRACT:
Modelling cable bolts as a means of reinforcement in rock masses has developed during last two decades. However a complete integration between a proper cable element model and software with the capability to model discontinuities of the rock mass has not been achieved. In this paper such an attempt is demonstrated and the capabilities of such an algorithm are demonstrated through some examples. By this tool, a blocky rock mass can be reinforced with fully grouted cable bolts with any length and load distribution along the cable can be determined as a function of rock mass movement. The effect of different cement grout properties or stress changes in the rock mass or different rock mass displacement profiles can be studied on the load distribution along the cable hence the reinforcement pattern can be designed optimally.
1 INTRODUCTION
Modelling the effect of reinforcement in rock masses is a difficult engineering problem that has seen significant improvement during last three decades. In this field, fully grouted reinforcement has more complexities than the other types since both the properties of the reinforcement system as well as the characteristics of the rock mass influence the bolt behaviour. There are widely reported observations that fully grouted reinforcement is more effective in hard rocks that behave as a discontinuum than in soft rocks. In particular, Bjornfot & Stephansson (1983) based on a comparison of their in situ instrumentation results in hard rock and Sakurai & Kawashima (1992) through some physical models and also Freeman’s (1978) results in soft rock, concluded that the behaviour of fully grouted reinforcement depends not only on the properties of the reinforcing system but also on the rock mass characteristics mainly its stiffness and distribution of displacements.
