Influence of material bridges on shear strength of unfilled intermittent rock joints

Abstract

According to the well-known Jaeger's theory, the minimum possible rock mass shear strength as a discontinuum actually corresponds to the shear strength of rock joints. Since failures in rock masses due to loads caused by civil structures or civil works occur mainly by exceeding their shear strength, the shear strength of rock joints has huge practical significance. Therefore, in this paper it was decided to analyse a factor which can have a very important influence on the shear strength of unfilled rock joints. Namely, the influence of the presence of material bridges and initial joints between them, their number, size, mutual distance and orientation relative to the shearing direction were analyzed using results of laboratory or numerical CNS direct shear tests which were carried out by different researchers around the world. Except for increasing its peak and residual value, the professional public is currently unaware of the impact of this factor on the shear strength of intermittent rock joints. Based on the carried out analysis, appropriate conclusions have been made.