Abstract Bolt shows the obvious anchorage effect on jointed rock mass and has become an irreplaceable reinforcement method in all kinds of rock engineering. The influence of bolt support structure on the fracture evolution behavior of rock is an important source of reinforcement effect. Therefore in this research, a series of experiments are conducted to reveal the influence of anchorage method on the fracture evolution mechanism of a non-persistent jointed rock mass. Firstly, the relations between AE and the evolution of the strain field of non-persistent jointed rock specimen are constructed, which illustrates a distinct effect of the joint angle and the anchorage method on the AE characteristics and the evolution of strain field. And then, the effect of the joint angle and the pre-tightening force on internal surface cracks and three-dimensional fracture modes obtained by X-ray CT observation is analyzed in detail. The results demonstrate that for anchorage specimens with smaller joint angles, tensile wing cracks are usually dominated; whereas for anchorage specimens with larger joint angles, tensile wing cracks are difficult to initiate and the shear cracks are usually dominated during the loading. For the same joint angle, the propagating path of cracks in the non-persistent jointed specimens can deflect more and the propagating length will decrease more with the increase of the pre-tightening force. Furthermore, the tensile cracks can transform the secondary shear cracks under higher pre-tightening force. Finally, the evolution of bolt axial force in the non-persistent anchorage jointed specimens is discussed in detail, which further reveals the effect mechanism of the joint angle and the pre-tightening force on the fracture characteristic of jointed rock mass.

中文翻译：

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DSCM、AE和X射线CT观测对具有多种锚固作用的非持久节理岩体断裂演化机制的试验研究

摘要 锚杆对节理岩体表现出明显的锚固作用，已成为各种岩石工程中不可替代的加固方法。锚杆支护结构对岩石断裂演化行为的影响是加固效果的重要来源。为此，本研究开展了一系列试验，揭示锚固方式对非持久节理岩体断裂演化机制的影响。首先，建立了声发射与非持久节理岩石试样应变场演化的关系，说明节理角度和锚固方法对声发射特征和应变场演化的影响是明显的。然后，详细分析了接头角度和预紧力对X射线CT观察得到的内表面裂纹和三维断裂模式的影响。结果表明，对于连接角较小的锚固试件，通常以拉伸翼裂纹为主；而对于具有较大接缝角度的锚固试件，在加载过程中，拉伸翼裂纹难以萌生，剪切裂纹通常占主导地位。对于相同的接头角度，随着预紧力的增加，非持久接头试件中裂纹的扩展路径偏转更多，扩展长度减小更多。此外，拉伸裂纹可以在较高的预紧力下转变二次剪切裂纹。最后，