不同法向应力下岩石节理面剪切损伤特性定量分析

Quantitative analysis of shear damage characteristics of rock joint surfaces under different normal stresses

摘要

基于剪切试验及3D轮廓扫描技术，探究了不同剪切加载条件下岩石节理面形貌、能量特征，并采用分形维数理论定量的分析节理面的损伤程度。结果表明：随着法向应力的增加，节理岩样峰值剪应力呈线性增长特征，且在高法向应力作用下，节理面微凸体的啮断破坏会造成剪切位移-剪应力曲线出现小幅波动特征；随着法向应力的增加节理面的剪切损伤区域依次呈现为细点状→点状→团块状→波浪状特征，其破坏模式逐渐由剪切磨损破坏转为磨损-剪断复合破坏；随着法向约束作用的增强，岩石节理剪切破坏所需驱动能量经历了快速增长和缓慢增长2个阶段，整体呈对数型增长趋势；同时，剪切节理面分形维数劣化值呈线性增长特征，节理面损伤程度增加显著。

Abstract

Based on shear test and 3D contour scanning technology, the morphology and energy characteristics of rock joint surface under different shear loading conditions were investigated, and the fractal dimension theory was used to quantitatively analyze the damage degree of joint surface. The results show that the peak shear stress of the jointed rock sample increases linearly with the increase of normal stress, and the shear displacement-shear stress curve fluctuates slightly due to the snapping failure of the asperities on the joint surface under the high normal stress; With the increase of the normal stress, the shear damage area of the joints surface shows the characteristics of small dot-like, dot-like, block-like and wavy, respectively, and the damage mode gradually changes from shear wear damage to wear-shear compound damage. With the enhancement of normal confinement, the driving energy required for shear damage of rock joints experienced two stages of rapid growth and slow growth, showing an overall logarithmic growth trend; meanwhile, the fractal dimensional degradation value of shear joint surface shows the linear growth characteristics, and the damage degree of joints increases significantly.

关键词

岩石力学 / 节理 / 3D扫描 / 分形维数 / 法向应力

Key words

rock mechanics / joints / 3D scanning / fractal dimension / normal stress