泥岩压剪破坏裂隙演化规律及其分形特征

 运用非线性分形理论，通过对自然含水状态泥试样品的变角剪切压模试验，研究泥岩压剪破坏裂隙演化规律和破裂块体分布的分形特征。研究结果表明：(1) 使用变角剪切压模试验数据绘制莫尔强度包络线可获得满意的岩石材料黏聚力和内摩擦角参数；(2) 压剪破坏的载荷–加载点位移曲线形状类似于岩石的全程应力–应变曲线，分为压密阶段、弹性阶段、塑性阶段和破坏阶段等4个阶段，可真实反映压剪耦合作用下岩块的变形破裂过程；(3) 压剪破坏是能量耗散的非线性动力学过程，破裂块体分布具有明显的自相似性，可用分形维数值表征破裂块体的块度分布特征；(4) 受破裂类型由张性破裂为主转变为剪切破裂为主的影响，随剪切角的增大，破裂块体分布的分形维数值呈对数关系递减。

FRACTURE EVOLUTIONARY RULES OF MUDSTONE UNDER COUPLED COMPRESSION AND SHEAR AND ITS FRACTAL CHARACTERISTICS

Based on the shear test with variable angle for pressure punch of mudstone samples in natural moisture condition，the fracture evolutionary rule and fractal characteristics of fracture blocks distribution of mudstone under compression and shear loading are studied by using nonlinear fractal theory. The research results are as follows：(1) The cohesion and friction angle parameters of rock samples are achieved by draw Mohr’s strength envelope according to the test date of shear test with variable angle for pressure punch. (2) The shape of load-load point displacement curves of rock sample under compression and shear loading is similar to complete stress-strain curve of rock sample under uniaxial compression，can be divided into compaction，elastic，plastic and fracture etc four stages，and faithfully represent the failure process of rock samples under coupled compression and shear. (3) Compression and shear failure is the nonlinear energy dissipation dynamics process，fracture blocks distribution has self-similarity obviously，and can use fractal dimension characterization its size distribution character. (4) Fractal dimension of fracture blocks distribution decrease logarithm with shear angle increase because of dominate fracture type transformed from splitting fracture into shear fracture.