ABSTRACT
Significant research have, in the past, been undertaken to study the mechanical behaviour of bolted rock joints, Spang and Egger (1991), Pallet and Boulon (1993), Ferrero (1995). Bjurstrom (1974) was the first to report on the systematic research work on fully grouted rock bolts. His shear tests were conducted on fully cement grouted bolts embedded in blocks of granite. According to Bjurstrom, inclining the bolt resulted in stiffening the shearing surface by increasing the shear strength at small displacement. Dight (1982) carried out a series of laboratory tests, to evaluate the shear resistance of bolted joints using various materials and he found that the normal stress acting on the joint surface had no influence on the shear resistance. Also, joints with inclined bolts were stiffer than the perpendicular ones. Dight (1982) proposed an expression to predict the maximum forces mobilized in the bolt. He also found that the failure of the bolt was caused by the combination of axial and shear forces. Ferrero (1995) proposed a shear strength model for reinforced rock joints based on both the numerical modelling and laboratory tests. The overall strength of the reinforced joint was considered to be the combination of both the dowelling effect and the incremental axial force increase due to the bar deformation. Also, Ferrero proposed a modified analytical model for bolts installed perpendicular to the joint plane in stratified bedding plane.
