单压下节理密度及倾角对类岩石试件强度及变形的影响

通过预制张开节理类岩石试件,在单轴压缩条件下,研究节理密度及倾角的组合作用对试件强度和变形特征的影响.试验结果表明:(1)随着节理倾角的增大,应力-应变曲线由多峰值转变为单峰值,试件脆性增强,延性减弱;(2)节理密度对当量峰值强度的影响与节理倾角大小有关,对当量弹模的影响呈“V”形变化,即当量弹模随着节理密度的增大呈现先减小后增大的变化规律;(3)当量弹模随节理倾角的增大而增大,在节理倾角为90°的时候达到最大值,为完整试件弹性模量的70%~80%;(4)节理倾角对多节理类岩石试件当量峰值强度和当量弹性模量的影响大于节理密度的影响.对试验结果进一步分析发现:节理密度及节理倾角与应力-应变曲线、当量峰值强度及当量弹性模量之间的关系,其变化规律与试件的破坏过程息息相关,其破坏模式可分为张拉破坏、剪切破坏和复合破坏.

Effect of the density and inclination of joints on the strength and deformation properties of rock-like specimens under uniaxial compression

The effects of the combination of joint density and inclination on the strength and deformation characteristics of rocklike specimens containing open joints were studied by using uniaxial compression tests. The following conclusions were made:with the increase of joint inclination, the stress-strain curve changes from a multi-peak value to a single peak value and the brittleness of the specimen enhances, whereas the ductility of the specimen weakens. The influence of joint density on the unified peak strength is related to the size of joint inclination, and the effect of joint density on the unified modulus shows a "V" shape, namely, the unified elastic modulus first decreases and then increases with the increase of joint density. With the increase of joint inclination, the unified elastic modulus increases gradually and its maximum value, which achieves 70%-80% of the complete specimens' elastic modulus, appears at 90° of joint inclination. The joint inclination is the major influencing factor on the unified peak strength and the unified elastic modulus of the rock-like specimens containing many joints. Further analysis on the test results demonstrates that the transformation law of the relationship between the joint density or joint inclination and the stress-strain curve, as well as the unified peak strength and the unified elastic modulus, is related to the failure process of the specimen. The failure mode of the specimen can be classified into three categories:tension failure, shear failure, and mixed failure.