Study on the bedding angle on the mechanical properties of shale

Abstract

Conventional mechanical tests under static loading can prove that the angle of the shale bedding plane is the main reason for the anisotropy of its mechanical behavior. In order to explore the influence of the angle in the layer on the anisotropic mechanical behavior of shale, the uniaxial compression mechanical tests were carried out under the conditions of 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that (1) the anisotropy degree of shale compressive strength shows the “W” type with the increase in the bedding angle, while the anisotropy degree of elastic modulus and Poisson’s ratio shows the “V” type with the influence of the bedding angle, but the minimum value of elastic modulus is around 45° and the minimum value of Poisson’s ratio is around 30°; and (2) the analysis of variance has a significant effect on compressive strength, elastic modulus, and Poisson’s ratio. Generally speaking, the anisotropic mechanical characteristics of shale have a great influence with the change in the bedding angle. The research conclusion is helpful to understand the mechanical behavior of shale.