为研究裂隙倾角和加载速率对岩石裂纹扩展及破坏模式的影响，采用中心钻孔法在50 mm×50 mm×100 mm的细砂岩试样上预制宽度范围为0°～90°的贯通裂隙，并对其进行声发射及摄影监测下单轴压缩试验和PFC数值模拟研究，综合分析其裂纹演化规律及变形破坏特征。结果表明：裂隙砂岩试样的破坏模式包含拉伸破坏、剪切破坏和拉伸/剪切混合破坏3种，根据裂纹起裂机理及发展轨迹可将其细化分为T1～4（拉伸）型、S1～3（剪切）型、M1～2（混合）型等9种类型，裂纹萌生亦可分为翼形裂纹、反抗拉裂纹、共面/非共面次级裂纹、横向裂纹等5种类型，且均与岩样加载破坏过程密切相关。岩样裂纹扩展及破坏模式受控于裂隙倾角α，随着α的增加，裂纹起裂应力升高，起裂位置由预制裂隙中央向尖端转移，裂纹前期萌生数量降低，岩样破坏模式由剪切破坏向拉伸破坏过渡。加载速率亦对岩样裂纹扩展及破坏模式产生影响，随着加载速率的增加，裂纹萌生类型由翼形裂纹变为反抗拉裂纹，且不再向其他裂纹类型转化，裂纹起裂时间缩短，破坏模式由剪切破坏向拉伸破坏过渡，岩样表面宏观裂纹数目降低。岩样的破坏过程与其声发射特征密切相关，声发射定位信息准确地反应了岩样的内部损伤情况。PFC数值模拟试验结果有效支撑了室内物理实验的结论，并反映出岩样裂纹萌生与扩展的根本原因是应力场的变化和转移，且压应力主要集中在预制裂隙尖端，而拉应力则主要集中在裂纹萌生的附近，一定程度上，拉应力场的分布揭示了裂纹萌生的主要趋势。

For the study of crack Angle and loading rate influence on rock crack propagation and failure mode,the center drilling method is adopted in 50 mm×50 mm×100 mm fine sandstone samples on precast transfixion crack width range of 0°-90°,and carries on the acoustic emission monitoring and photography order axial compression test and PFC numerical simulation research,comprehensive analysis of the evolution regularity of crack and deformation and failure characteristics.Results show that the fracture failure mode in the sandstone sample containing the tensile failure and shear failure and tensile/shear mixing three kinds of damage,based on the mechanism of crack crack and refine its trajectory can be divided into T1-4(tensile),S1-3(shear),M1-2(mixed) 9 types,such as crack initiation can be divided into the wing crack,crack,resistance to pull coplanar/non coplanar secondary crack,transverse crack,such as five types,and are closely related to the sample loading failure process.The crack propagation and failure mode of rock sample is controlled by the crack angle α.With the increase of α,the crack initiation stress increases,the crack initiation location transfers from the center of the prefabricated crack to the tip,the number of crack initiation decreases in the early stage,and the rock sample failure mode transfers from shear failure to tensile failure.Loading rate and the initial crack extension and failure mode effect,with the increase of loading rate,crack initiation type changed from wing crack to crack resistance,and not to other types of crack,crack crack a shorter time,to make the transition to tensile failure of failure by shear failure mode by sample surface macroscopic crack down.The damage process of the rock sample is closely related to its acoustic emission characteristics and the acoustic emission location information accurately reflects the internal damage of the rock sample.PFC numerical simulation experiment results support the indoor physical experiment conclusion effectively,and reflects the rock crack initiation and extension and transfer is the root cause of the change of stress field,and the compressive stress is mainly concentrated in the prefabricated crack tip,and the tensile stress concentrated near the crack initiation,to some extent,the distribution of tensile stress field reveals that the main trend of crack initiation.

1 试验方案

   1.1 试验材料和试样制备

   1.2 试验设备和试验方法

2 细砂岩试样裂纹演化及破坏特征

   2.1 裂纹扩展与应力-应变曲线的对应关系分析

   2.2 裂隙岩样裂纹演化与破坏模式分析

   2.3 裂隙岩样裂纹演化与声发射信息的对应关系

3 数值模拟结果与分析

   3.1 数值模型构建

   3.2 岩样破坏特征对比与分析

   3.3 裂纹扩展的加载速率效应

4 结论