页岩力学性质各向异性初探

Anisotropic Investigation of the Mechanical Property of Shale

对不同层理倾角页岩进行单轴实验获得力学参数,研究页岩的各向异性强度特征及变形各向异性特征。并利用离散元软件PFC2D对含有层理的页岩进行数值模拟,实现对页岩力学参数的确定,从而研究含有不同角度单一层理和一组层理的页岩抗压强度各向异性。结果表明,随着层理倾角增大,页岩单轴抗压强度先减小后增大,层理弱面效应明显;单一层理模型抗压强度曲线为"单肩型",一组层理模型抗压强度先缓慢减小,再急剧减小,然后急剧增大;含有层理的页岩破坏形式主要表现为3种:一是端面小范围的剪切破坏,二是沿层理面发生滑动的剪切破坏,三是沿层理面发生劈裂破坏。对于含有一组平行层理的页岩模型,两侧层理相对于中间层理弱面效应更加明显,层理弱面增多,抗压强度减小。

The anisotropic investigation of shale strength and deformation is performed on the rock with different bedding angle which are obtained via the uniaxial compression test. The anisotropic investigation of compressive strength on shale is studied from different degree of single bedding and group bedding. The mechanical parameter of shale is simulated by discrete element software PFC2D. Results shows that when bedding angle increases, the uniaxial compressive strength decreases first then increases; the bedding inclination effect is obvious; the compressive strength curve of single bedding model presents like ＇ single shoulder＇ model, and the compressive strength curve of group bedding model slowly decrease first, then decrease sharply, finally increases sharply; There are three kinds of destruction patterns of shale bedding, shear failure occurs to small-scale specimen head, sliding shear failure along the bedding plane, splitter failure along the bedding plane; For a shale model with group bedding plane, the bedding inclination effect on the sides of bedding plane more obvious than the middle, the weak bedding planes increasing while the compressive strength is decreasing.