Improved Nonlinear Strength Criterion for Jointed Rock Masses Subject to Complex Stress States

Abstract

Prediction of rock mass strength is important for estimating stability in rock engineering projects. In this paper, a novel strength criterion was proposed to determine the strength of a jointed rock mass subjected to a complex stress state. First, a series of tests were carried out on specimens with different joint geometries and under different confining pressures. From these tests, the factors affecting the strength of the jointed rock mass were obtained. The experimental results showed that normalized strength decreases initially and then increases as joint inclination angle increases, and it increases consistently and nonlinearly with increasing normalized confining pressure. Based on the experimental results, an improved nonlinear strength criterion was presented to describe the combined influence of the two aforementioned factors on jointed rock mass strength, and methods for determining the involved parameters were also introduced. Furthermore, multiaxial test data from the literature and biaxial test data from this paper were used to validate the feasibility and reliability of the new criterion. The results showed that the new criterion can predict the strength of jointed rock with high accuracy.