A Parametric Analysis on the Influence of the Binder Characteristics on the Behaviour of Passive Rock Bolts with the Block Reinforcement Procedure

An extensive parametric analysis of 729 typical cases was developed with a calculation procedure allowing to simulate in detail the behavior of the passive bolts and their interaction with the surrounding rock. The parametric analysis allowed to evaluate the effectiveness of the bolts, on the basis of the extent of the stabilization forces produced, in relation to the geometric and mechanical characteristics of the binder used in the realization of the bolts. Different bolt diameters and lengths, binder thickness and elastic moduli and block displacement values with respect to the horizontal plane have been considered. It has been possible to detect how such parameters have a great influence on the mechanical behavior of the bolt and on the extent of the stabilizing forces which are applied to the potentially unstable rock block. For this reason, therefore, the definition of the characteristics of the binder (and in particular the thickness of the binder around the steel bar and the elastic modulus of the binder itself) cannot be assessed only in relation to application aspects, but it must be able to consider the effects on the efficiency of the bolt and in particular on the stabilization forces on the potentially unstable rock block.