Failure of rocks under tensile conditions

Abstract This paper examines, theoretically and experimentally, a number of systems in which extension failures occur under applied compressive loads. These are (i) compression of a circular cylinder along two diameters or by three symmetrically placed line loads (ii) diametral compression of spheres and cubes (iii) bending of circular plates. In all these cases, one principal stress is tensile over a portion of the body and failure occurs in this region: in many cases the calculated maximum tensile stresses in the region are of the order of the uniaxial tensile strength of the material. For circular plates, as for other cases of inhomogeneous stresses, they are higher. Many of these systems are related immediately to the crushing of single particles or aggregates of particles.