压剪作用下多节理类岩试样力学性质及破坏判据

Mechanical properties and failure criteria of multi-joint rock-like specimens under compression-shear

为研究骨料粒径及节理倾角对岩体的力学性质影响,采用两种不同粒径骨料的砂浆制作不同倾角平行节理试样进行压剪试验,并利用声发射系统监测试样加载过程。试验结果表明:骨料粒径增大,试样的峰值剪切强度增大;随节理倾角增大,粗颗粒试样的峰值剪应力呈先增加后减小的趋势,细颗粒试样的峰值剪应力呈增―减―增―减的规律;声发射计数随试样加载呈现规律变化,其在试样峰值剪应力后达到最大值。利用Mohr-Coulomb破坏准则建立岩石压剪断裂判据。经分析,裂纹尖端应力强度因子比值KⅡc/KⅠc值只与岩石材料的内摩擦角?有关,且KⅡc/KⅠc值随内摩擦角?增加而增大。

This paper is aimed to study the influence of aggregate size and inclination angle of joints on the mechanical properties of rock mass. Mortars with two aggregate sizes were used to prepared joint specimens with different inclination angles. Meanwhile, the loading process was monitored by the acoustic emission system. The experimental results showed that the peak shear strength of the specimens increased with the increase of the aggregate size. The peak shear stress of the coarse particle specimen increased firstly and then decreased. However, the peak shear stress of the fine particle specimen exhibited an increasing-decreasing-increasing-decreasing trend. The acoustic emission changed with the loading of the specimen, and reached the maximum value after the peak shear stress.Rock shear fracture criterion was established according to Mohr-Coulomb failure criterion. The stress intensity factor ratio at crack tip( KⅡc/KⅠc) was found to be only related to the internal friction angle of the rock-like material, and the value of KⅡc/KⅠcincreased with the increase of the internal friction angle.