ABSTRACT
This chapter explains how to calculate the vertical stress and discuss the major failure criteria that engineers use to assess the rock strength. It also explains how to analyze lab data using different failure criteria. Unlike soil mass, the horizontal stresses in rock mass are mostly due to tectonic activities, and they can be greater than the vertical stresses. The Mohr-Coulomb failure criterion is used for rock, in which failure occurs in shear. The Barton criterion is used to estimate the shear strength of jointed rock mass. The friction between two joints can be estimated by means of a tilt test using smooth unweathered rock surfaces. The friction between two joints can be estimated by means of a tilt test using smooth unweathered rock surfaces. The shear strength of jointed mudstone will be estimated using the Barton shear strength criterion.
