为了探究不同粗糙度断续节理岩体直剪试验的裂纹扩展过程及破坏模式,基于颗粒流方法,对试样施加不同法向应力,并探讨了预剪面应力演化过程。研究结果表明:根据微观裂纹的张、剪属性及其演化过程,岩桥破坏模式大体可分为5类,且与法向应力和节理面粗糙度密切相关,法向应力、节理粗糙度的增加都会促使岩桥向剪切破坏方式转变;初始翼裂纹与原节理面的夹角对法向应力变化不敏感,而随着节理粗糙度的增加而减小;在剪切过程中,预剪面上的应力分布不均匀且不断进行重分布,对于平直节理岩体剪应力主要由岩桥承担,且无论水平向还是法向,岩桥部分压应力均大于节理部分;而对于粗糙节理岩体,剪应力由节理和岩桥共同承担,且节理部分的应力均高于岩桥部分。研究成果对进一步明确断续节理岩体的力学参数有参考价值。
Abstract
The crack propagation process and failure mode of discontinuous jointed rock mass with different roughness coefficients under different normal stresses are studied via particle flow method, and the stress evolution process of pre-shearing plane is discussed. Results reveal that the failure modes of rock bridge can be roughly divided into five categories according to the tensile and shear properties of micro-cracks and their evolution process, which are closely related to the normal stress and joint surface roughness coefficients. The increments in normal stress and joint surface roughness coefficients would instigate rock bridge towards shear failure. The angle between the initial wing crack and the original joint surface is not sensitive to the change of normal stress; but declines with the increase of joint roughness coefficients. In the shearing process, the stress on the pre-shearing plane does not distribute uniformly and meanwhile redistributes continuously. The shear stress of flat jointed rock mass is mainly borne by rock bridge, and the compressive stress of the rock bridge is greater than that of the joint in both horizontal and normal directions, while for rough jointed rock mass, the shear stress is borne by both the joint and the rock bridge, and the stress of the joint part is higher than that of the rock bridge.
关键词
断续节理岩体 /
节理粗糙度 /
分形模型 /
岩桥 /
破坏模式
Key words
discontinuous jointed rock mass /
joint roughness coefficient /
fractal model /
rock bridge /
failure mode
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