摘要
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。
A conceptual model of soft rock in the red layer regions of China is developed with considering the softening characteristics and the mesoscopic images of the rock. Based on this, the characteristics of friction and contacts （including static and kinetic frictions） in the soft rock is analyzed. The maximum coefficient of static friction increases with the increase of actual contact area, normal stress and residence time, whereas the kinetic friction increases with the sudden increase of velocity. For the indirect contact particles, the tangential stress is mainly dependent on the shear strength of clay minerals which is dominated by the friction coefficient and adhesive strength. Furthermore, the water softening of skeleton particles is analyzed, it is found that hydration weakening effects mainly show as changing the contact stress between skeleton particles as well as degrading clay mineral particles, namely, the water reduces the effective stress between skeleton particle and clay mineral particle, and hence both the cohesion and internal friction angle of clay minerals. Owing to this, the friction between the particles and the strength of soft rocks decreases, and the soft rock becomes weaker. The above results can be reflected, to a certain extent, by the compression process of the soft rock under the triaxial compression test.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2015年第9期2458-2466,共9页
Rock and Soil Mechanics
基金
国家自然科学基金重点项目
面上项目(No.41030747
No.41372302)
国家自然科学基金仪器专项(No.41227002)
广东省自然科学基金重点项目(No.S2011020001229)
关键词
软岩
水-应力作用
细观结构
摩擦接触
遇水破坏
soft rock
water-stress action
mesostructure
frictional contact
water damage
