DRAINED SHEAR BEHAVIOUR OF INFILLED ROCK JOINTS

Abstract

The rock masses behaves as discontinuum due to the presence of discontinuities such as joints, faults, shear zones etc. The most important factor is the shear strength of potential failure planes. The presence of filled material influences significantly the shear strength of infilled discontinuities is perhaps one of the complex problems. The main difficulty is due to the increased number of variable parameter which influence the shear strength of infilled jointed rock masses. In the present work, the results of a series of direct shear tests conducted under drained conditions at strain rate of 0.125 mm/min on modeled infilled discontinuity are reported. Cement is selected as parent model material. The discontinuity simulated having asperity angle 300 and mean roughness amplitude of 4 mm is then filled with china clay and fly ash in different thickness and tested under controlled conditions. It is shown that peak shear strength decreases with increasing fill thickness (t) and approaches to a minimum when t/a (thickness-amplitude ratio) is between 1.9 and 2.5 depending on normal stress. The validity of results have also been checked with Papliangas et al. (1993) and Deepankar (1994).