单轴压缩下页岩力学特性的各向异性试验研究

为了研究页岩的物理力学特征及其各向异性，为掌握页岩气开采过程中水力压裂网状裂隙的扩展规律提供技术参数，开展了龙马溪组页岩的电镜扫描和单轴压缩试验，分析了基于不同层理面页岩的微观结构、力学参数、破坏特征等各向异性。结果显示：页岩的各向异性是其固有特征，且该特征决定了页岩的力学性质、破坏模式均表现出各向异性。当取芯方向与层理面夹角θ=0°时，破坏模式为张拉破坏；当θ=22.5°时，为沿着层理面的剪切破坏和平行于轴向方向的张拉破坏；当θ=45°时，为沿着层理面的单一剪切破坏；当θ=67.5°时，为沿着层理和贯穿层理的复杂剪切破坏；当θ=90°时，为贯穿层理面的张拉破坏。页岩的纵波波速、弹性模量、单轴抗压强度以及泊松比也都表现出一定的各向异性。

Anisotropic Experimental Study on Mechanical Properties of Shale under Uniaxial Compression

In order to study the physical mechanical characteristics of shale and its anisotropy，and provide technical parameters for hydraulic fracturing process regularity of fissure network，the electron microscope scanning and uniaxial compression tests for Longmaxi formation shale are carried out to analyze its anisotropic property based on the different bedding plane microstructure，mechanical parameters and damage characteristics.The results show that：the anisotropy of shale is its intrinsic property，which determines different mechanical properties of shale and failure mode.When the angle of the coring direction and bedding plane θ=0°，the failure mode shows as tension destruction；θ=22.5°，the failure mode is the shear failure along the bedding plane and the tensile destruction parallel to the axial direction；θ=45°，the failure modes is the single shear failure along the bedding plane；θ=67.5°，the failure mode is the complex shear failure along or through the bedding plane；θ=90°，the failure mode is the tension destruction through the bedding plane.The longitudinal wave velocity，elastic modulus，uniaxial compressive strength and Poisson ratio also show some anisotropy.