地下矿山采空区顶板等地下工程岩体常面临拉剪破坏灾害，而目前对拉剪应力状态下裂隙 岩体的破坏机制认识不深。 为了探究裂隙岩体拉剪破坏规律，利用自主研制的拉剪辅助装置开展 了单裂隙砂岩试样在法向拉应力条件下的直接剪切试验。 结果表明:裂隙与水平剪切方向的夹 角(逆时针方向，简称“裂隙角”)对拉剪强度及裂纹扩展形态有明显影响。 随裂隙角从 0°~180°变 化，强度总体上先增大后减小，最大值出现在裂隙角为90°~120°。 当裂隙角为锐角时容易发育从 试样边缘开始的次生裂纹与裂隙端部发育的主裂纹形成成核破坏，而当裂隙角为钝角时仅从裂隙 端部发育裂纹，裂纹路径相对较水平。 随裂隙角从0°~180°变化，起裂方向角先减小后增大，当裂 隙角为 30°时最小。 随着法向拉应力增大，裂纹较水平，起裂方向角总体上呈增大趋势。 试样破坏 以翼裂纹的拉伸破坏为主，当裂隙较陡时裂纹可从裂隙内部起裂扩展，这与压剪情况下试样破坏以 剪切破坏或张拉-剪切混合破坏为主，当裂隙角为钝角时可出现反翼裂纹相比具有明显差异。 通 过 DIC(数字图像相关)观测，分析了应变演化和位移场特征。 随着剪应力的施加，预制裂隙处应变 集中区域逐渐从中部向裂隙两端延展，裂纹沿着应力集中区域的内边缘起裂扩展。 预制裂隙受到 的应力状态与裂隙角有较大关系。 裂隙角为 90°以下时，随着裂隙角增大，预制裂隙从受拉至拉剪 再到剪切变化，裂隙角为 90°以上时仅受拉剪;而不同裂隙角时扩展裂纹的力学属性均以张拉为 主。 研究揭示了拉剪应力状态下裂隙岩体裂纹扩展特有的规律，可为地下岩体工程开挖稳定性评 价提供理论参考。

The rock mass of underground engineering such as the roof of underground mined⁃out area is often faced with tensile⁃shear failure disaster. However，the failure mechanism of fractured rock mass under tensile⁃shear stress state is currently not well understood. To investigate the tensile⁃shear failure law of fractured rock mass，a self⁃devel⁃ oped tension⁃shear auxiliary device was used to carry out the direct shear tests of sandstone specimens containing a single fissure under normal tensile stress conditions. The results show that the angle between the fissure and the horizontal shear direction (anti⁃clockwise direction，“fissure angle” for short) has a great influence on the tensile⁃shear strength and crack propagation form. As the fissure angle varies from 0° to 180°， the strength increases first and then decreases，and the maximum appears in the range of fissure angle from 90° to 120°. When the fissure angle is an acute angle，it is easy to develop secondary cracks from the edge of the specimen to form a nucleation failure with the primary crack developed at the end of the fissure. When the angle is obtuse，cracks only develop from the end of the fissure，and the crack path is relatively horizontal. As the fissure angle varies from 0° to 180°，the cracking di⁃ rection angle first decreases and then increases and the minimum cracking direction angle is reached when the fissure angle is 30°. With the increase of the normal tensile stress，the cracks are more horizontal，and the cracking direction angle generally increases. The specimen failure is mainly the tensile failure by the wing cracks. When the fissure is steep，the crack can start and expand from the inside of the fissure. The difference between the tension⁃shear and com⁃ pression⁃shear failure is obvious. In the case of compression⁃shear，the specimen failure is mainly shear failure or ten⁃ sion⁃shear mixed failure. Anti⁃wing cracks can appear when the fissure angle is obtuse. Through DIC (digital im⁃ age correlation) observation，the strain evolution and displacement field characteristics were analyzed. With the appli⁃ cation of shear stress， the strain⁃concentrated area at the prefabricated fissure gradually extends from the middle to the two ends of the fissure，and the crack starts to expand along the inner edge of the stress⁃concentrated are⁃ a. The stress state of the prefabricated fissure has a great relationship with the fissure angle. When the fissure angle is below 90°，as it increases，the stress state of prefabricated fissure changes from tension to tension⁃shear and then to shear. When the fissure angle is above 90°，the stress state is tension⁃shear. However，the mechanical properties of propagating cracks under different fissure angles are mainly tensile. The study reveals the unique law of crack propaga⁃ tion of fractured rock mass under tensile⁃shear stress state，which can provide a theoretical reference for the stability evaluation of underground rock mass excavation.