Determination of Shear Failure Envelope in Rock Masses

In this work, an analytic expression has been developed that enables the shear strength to be determined using the empirical failure criterion developed by Hoek and Brown. Applying this new hypothesis, along with elasticity theory and basic mathematical concepts for obtaining the failure envelope of a family of failure circles, the shear strength has been determined to be such that ${\tau }_{\alpha }=f\left({\sigma }_{\alpha }\text{,}{\sigma }_c\text{,}m\text{,}s\right)\text{,}$ where ${\sigma }_{\alpha }=\mathrm{the}$ normal stress on the discontinuity, ${\sigma }_c$ the uniaxial compressive strength of the intact rock and the parameters m and s are constants dependent upon the properties of the rock. An expression of this type will help us develop new methods of analysis of slope stability and support of galleries, design of anchor support systems in rock masses, estimation of the skin friction of poor quality rock in driven pile foundations, as well as in other innumerable related areas of geotechnology.