Abstract:
The shear strength of rock discontinuities is a critical parameter in rock engineering projects
for assessing the safety conditions of rock slopes or concrete dam foundations. It is primarily
controlled by the frictional contribution of rock texture (basic friction angle), the
roughness of discontinuities, and the applied normal stress. While proper testing is essential
for accurately quantifying shear strength, engineering geologists and engineers often
rely on published historical databases during early design stages or when test results show
significant variability. This paper serves two main objectives. First, it intends to provide
a comprehensive overview of the basic friction angle concept from early years until its
emergence in the Barton criterion, along with insights into distinctions and misunderstandings
between basic and residual friction angles. The other, given the influence of the basic
friction angle for the entire rock joint shear strength, the manuscript offers an extended
database of basic friction angle values.
