不同层理方位影响下板岩各向异性巴西圆盘劈裂试验研究

RESEARCH ON BRAZILIAN DISC SPLITTING TESTS FOR ANISOTROPY OF SLATE UNDER INFLUENCE OF DIFFERENT BEDDING ORIENTATIONS

通过电镜扫描试验,发现板岩具有明显的变余层理构造和板劈理构造,因而可采用巴西圆盘劈裂试验揭示其力学特征。对7种不同层理角度下的圆盘进行劈裂试验,得到圆盘的3种破坏形式:<45°为纯拉伸破坏,=45°～75°为剪切拉伸破坏,>75°为剪切破坏。同时,板岩受内部层理构造的影响,其抗拉强度随值从0°变化到90°而逐渐降低;垂直于各向同性面的弹性模量和泊松比受层理角度影响不大,且前者比各向同性面的弹性模量值略小。

According to electron microscopy scanning experiments, it is found that slate has significant blasto-stratification structures and plate cleavages structure. As a result, mechanical characteristics of slate can be revealed by Brazilian disc splitting tests. Based on the disc splitting tests under seven different kinds of bedding angles θ, three kinds of failure forms of disc can be obtained as follows： pure tensile failure when the bedding angle θ〈45°, shearing failure when the bedding angle θ〉75°, and both tensile and shearing failure when the bedding angle θ is between 45 ° and 75°. Meanwhile, Because of the impact of internal bedding structure on the slate, tensile strength of the slate gradually decreases with the bedding angle θ varying from 0° to 90°. Moreover, the bedding angle has a slight influence on the elastic modulus and Poisson＇s ratio perpendicular to the isotropic plane; and the elastic modulus perpendicular to the isotropic plane is slightly smaller than that of the isotropic plane.