单轴压缩条件下交叉双节理岩石裂纹扩展特征颗粒流分析

Particle flow analysis of crack propagation characteristics of cross jointed rock under uniaxial compression

为研究交叉节理对岩石强度及破裂特征的影响,对含交叉节理岩样进行单轴压缩模拟,探讨不同交叉方式及交叉夹角对试样力学特性及裂纹扩展特征的影响规律。采用颗粒流程序PFC^(2D)构建试样数值模型,并通过与完整试样室内试验结果进行比较,标定能够反映岩样力学特性的细观参数。在此基础上,对含X,L和T型交叉节理的3种试样进行单轴压缩模拟。研究结果表明:(1)3种交叉方式的单轴抗压强度、峰值应变和弹性模量均与交叉角度呈现良好的线性负相关,其中,L型受交叉角度影响最大。(2)3种交叉方式的裂纹扩展规律相似,且试样破坏模式基本呈张拉破坏。3种交叉方式的微裂纹数量变化及破坏程度均受交叉角度影响显著。(3)交叉双节理试样破坏时各微裂纹占比大小基本稳定,交叉双节理岩石在单轴压缩作用下细观结构的破坏形式主要以张拉破坏和剪切破坏为主。研究成果对于保障滇中引水香炉山隧洞的顺利贯通提供一定的理论基础,也可为类似工程提供参考。

In order to study the influence of cross joints on rock strength and fracture characteristics,the simulation of specimens containing cross joints under uniaxial compression was carried out to explore the influence of cross angle and cross way of cross joints on the mechanics characteristics and crack coalescence behavior.A simulation model of sample was established in particle flow code PFC^(2D),based on the experimental results of intact specimens,a set of microscopic parameters that can reflect the mechanical properties of sample were obtained.Then,the uniaxial compression tests of the specimens with X-type,L-type and T-type cross joints.The results are as follows:(1)The uniaxial compressive strength,peak strain and elastic modulus of three cross-type specimens show a good linear negative correlation with the cross angle,especially the L-type.(2)The crack coalescence behavior of three cross-type specimens is similar,and the failure mode is basically tensile failure.The number of microcracks and the damage degree of three cross-type specimens are significantly affected by the cross angle.(3)The proportion of each microcrack is basically stable when the specimens containing cross joints are failure.The failure modes of meso-structure of the specimens containing cross joints under uniaxial compression are mainly tensile failure and shear failure.The results provide a certain theoretical basis for the penetration of the Xianglushan tunnel in Central Yunnan Water Diversion Project,and can also provide reference for similar projects.