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针对我国南方地区红层软岩变形破坏特点,在典型软岩细观结构显微观察试验基础上,概化出其细观结构模型,据此探讨软岩骨架颗粒摩擦接触关系,包括直接和间接摩擦接触两种关系:(1)直接摩擦接触分为静摩擦接触和动摩擦接触两个过程考虑,静摩擦接触中的最大静摩擦系数会随着实际接触面积、法向荷载、停留时间增大而增大;动摩擦接触中的动摩擦系数则随着速度突然增大而增大。(2)间接摩擦接触作用主要体现在黏土矿物的抗剪强度上,其主要由充填其间的黏土矿物颗粒间的摩擦系数和黏结强度决定。在此基础上,研究水对软岩骨架颗粒摩擦的弱化作用:水的弱化作用主要体现在对骨架颗粒接触应力的改变和黏土矿物本身的弱化效应,具体表现为水作用下骨架颗粒与黏土矿物间的接触应力降低、黏土矿物的黏聚力和内摩擦角减小。这一弱化效应将有效降低软岩骨架颗粒间的摩擦力,从而造成软岩结构强度降低,使得破坏过程更容易发生。以上分析可以在一定程度上反映软岩三轴压缩试验过程。
Aiming at the characteristics of deformation and failure of the soft rock in the south of China, based on the microscopic observation of the typical soft rock microstructure, the mesostructural model is generalized to investigate the frictional contact between the soft rock and the skeleton, including direct and indirect There are two kinds of frictional contact: (1) The direct frictional contact is divided into two processes, static friction contact and dynamic friction contact. The maximum static friction coefficient in static friction contact increases with the actual contact area, normal load and residence time. Dynamic friction coefficient in the dynamic friction coefficient increases with the sudden increase in speed. (2) The indirect frictional contact is mainly reflected in the shear strength of clay minerals, which is mainly determined by the friction coefficient and the bond strength between the clay minerals filled in the clay. On this basis, we study the weakening effect of water on the friction of soft rock matrix particles: the weakening effect of water is mainly reflected in the change of the contact stress of the framework particles and the weakening effect of the clay minerals themselves, specifically, the interaction between the framework particles and the clay minerals Between the contact stress decreases, the clay mineral cohesion and internal friction angle decreases. This weakening effect will effectively reduce the friction between the soft rock skeleton particles, resulting in reduced soft rock structure strength, making the destruction process easier to occur. The above analysis can to some extent reflect the soft rock triaxial compression test process.