为研究节理和孔洞对岩体的力学特性影响规律，通过完整砂岩与含预制单裂隙砂岩试样室内单轴压缩试验和颗粒流程序PFC2D模拟试验试样的弹性模量和峰值强度等相关参数以及最终破坏模式的对比分析，最终选取了一组合理的细观参数，并采用该组细观参数对孔洞式三叉裂隙试样进行单轴压缩模拟试验。研究结果表明:随着裂隙倾角α、裂隙倾角β、孔洞直径d和裂隙长度2a的改变，孔洞式三叉裂隙试样的峰值强度和峰值应变呈非线性变化，且它们均显著低于完整试样，其中裂隙长度2a对试样的峰值强度影响最大。孔洞式三叉裂隙试样在加载过程中发生拉伸和剪切破坏，且主要以拉伸破坏为主;翼形裂纹一般萌生在预制三叉裂隙的外尖端或距其外尖端一定位置和预制三叉裂隙与孔洞交接处附近位置，次生裂纹一般萌生在翼形裂纹扩展过程中的某个位置或试样的边界部位;裂隙倾角α主要影响试样的破坏程度，裂隙倾角β主要影响裂纹的扩展模式，孔洞直径d主要影响次生裂纹的萌生位置，裂隙长度2a主要影响翼形裂纹的萌生位置;通过对孔洞式三叉裂隙试样裂纹扩展机制探讨，裂隙试样在初始裂纹萌生阶段，应力集中区一般产生在预制三叉裂隙尖端附近和孔洞边缘，并且伴随在试样内部产生声发射事件，最后随着应力的不断增加和应力场的不断演化，微裂纹逐渐汇集形成的宏观裂纹不断扩展最终导致了试样的失稳和破坏。

In order to study the influence of joints and holes on the mechanical properties of rock mass,this paper selects a group of reasonable micro parameters by comparing and analyzing the elastic modulus,peak strength and the final failure mode of the intact sandstone and the sandstone samples with prefabricated single fracture in the laboratory uniaxial compression test and the PFC2D simulation test.The micro parameters are used to carry out the uniaxial compression simulation test on the holetype trident crack sandstone.The results show that the uniaxial compression strength and uniaxial compression strain of the fracture specimens are nonlinear with the change of the crack angle α,the crack angle β,the hole diameter dand the crack length 2a,and they are significantly lower than those of the intact specimens,and the crack length 2a has the greatest influence on the uniaxial compression strength of the specimens.Tensile and shear failure occurs during loading,and the main failure mode is tensile failure.The  wing cracks generally originate at the outer tip of prefabricated trident cracks or near the junction of refabricated trident cracks and hole,while the secondary cracks generally originate at a certain location during the growth of wing cracks.The crack angle α mainly affects the damage extent of the specimen,the crack angle β mainly affects the propagation mode of the crack,the hole diameter d mainly affects the initiation position of the secondary crack,and the crack length 2a mainly affects the initiation position of the wing crack.Through the discussion of the crack growth mechanism of the holetype trident fracture sandstone,in the initial crack initiation stage,the stress concentration region of the specimen generally occurs near the tip of prefabricated trident crack and the edge of the hole,with the acoustic emission events in the specimen,and finally,with the continuous increase of stress and the evolution of stress field,the continuous propagation of the macrocracks formed by the gradual convergence of microcracks eventually leads to the instability and failure of the specimen.

1 颗粒离散元模型的构建

    1.1 PFC模拟方法

    1.2 数值模型构建

2 细观参数验证

    2.1 单裂隙砂岩数值模拟与室内试验力学参数对比

    2.2 单裂隙砂岩模拟与室内试验破坏特征对比

3 孔洞式三叉裂隙砂岩力学行为的颗粒流分析

    3.1 力学参数特征分析

    3.2 裂纹扩展特征分析

4 裂纹扩展机制讨论

    4.1 裂纹扩展过程与声发射的关系

    4.2 裂纹扩展过程与应力场分布的关系

5 结论