Relation between the shear and uniaxial strength of rock materials
The trap, in the translating formulation of the shear strength parameters(cohesion c, friction angle ϕ) and uniaxial strength parameters (tensile strength σt compressive strength σc) of rocks as Crude Kuroiwa, sandstone and etc., is discussed by comparing with the relative parameters measured from experiments. A statistical formula between the parameters of the deduced and measured uniaxial strength is represented, and a theoretical formula is derived and verified in the transmission process between the deduced and measured shear strength parameters.
Strength of rock-like materials
Abstract This paper deals with the strength of rock-like materials under triaxial stress conditions. The most common theories of brittle fracture are reviewed. Some methods of triaxial strength determination are described and the results compared. The strength dependence of lateral pressure, pore pressure and size of the test sample is described. Some standard tests are suggested. A method for determining the shear strength at high normal pressure has been used as a measure of the strength of a number of Swedish rocks and ores.
A fracture criterion for brittle anisotropic rock
The McClintock-Walsh modification of Griffith theory is extended to treat brittle fracture of anisotropic rock. It is suggested that anisotropy is due primarily to preferred orientation of cracks in rocks and that a satisfactory mathematical model for fracture analysis is an elastically isotropic medium which contains a nonrandom array of Griffith cracks. The one array considered in detail consists of long cracks having a preferred orientation superimposed on a field of randomly oriented small cracks. Fracture in tension and in compression is considered. The fracture criterion found for compression resembles a similar criterion suggested by Jaeger on a somewhat different basis; it predicts behavior which is in good agreement with observed fracture of a slate reported by Donath. Determination of the effect of anisotropy upon the ratio of compressive strength to tensile strength shows that it can vary widely with sample orientation, with values both above and below that predicted from isotropic analysis.