Features of shear failure of brittle materials and concrete structures on rock foundations

The failure of brittle materials under compressive shear loading is described mainly on the basis of experimental investigations. The failure is accompanied by the formation of a combined fracture of a curvilinear or broken line shape, developing along the trajectories of the principal planes. A primary tensile crack is formed along the principal tensile stress planes. A thin streak or tight crack named a compressive crack develops along the principal compressive stress planes. Formation of the compressive crack coincides with a limiting condition, the peak shear strength τp. Reasons for the discordance of conventional shear theories as applied to brittle materials are discussed. The criterion of a material strength parameter, crushing resistance Rcr, is proposed and corrections are introduced into traditional methods of analysis of concrete dam stability. Examples of engineering applications of the failure features obtained are given.