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首页> 外文期刊>Tunnelling and underground space technology >Study of the fracture behavior of mode I and mixed mode Ⅰ-Ⅱ cracks in tunnel under impact loads
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Study of the fracture behavior of mode I and mixed mode Ⅰ-Ⅱ cracks in tunnel under impact loads

机译：冲击荷载作用下隧道I型和Ⅰ-Ⅱ型混合裂纹的断裂行为研究

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摘要

Blast excavation may induce radial cracks around a tunnel, and these cracks may initiate and propagate under nearby mining activities. In order to study the dynamic fracture behavior of mode I and mixed mode I/II cracks in a tunnel under impact loads, a new large sample, i.e. a tunnel with a radial crack (TWSRC) was proposed. Impact tests by using the TWSRC samples and a drop-weight impact testing device were also implemented. The advantage by using the TWSRC samples is that the corresponding results could be directly employed to tunnel engineering practice, and could lead tunnel designers to improve tunnel dynamic stability and to prevent tunnel hazards. The pre-crack was designed in a tunnel roof and was parallel to the symmetrical axis of the tunnel. The ratio a of the distance between the crack and the symmetrical axis to the radius of tunnel roof was in the range between 0 and 1. The crack initiation time and the crack propagation characteristic were measured by strain gauges and crack propagation gauges. A finite difference commercial code AUTODYN was used in the simulation of crack propagation paths and the fracture mechanism was analyzed. A finite element commercial code ABAQUS was employed to calculate crack dynamic stress intensity factors (DSIFs), and the experimental-numerical method was used to measure crack initiation toughness. The results showed that for mode I cracks, the cracks propagate along the pre- exiting crack direction, whereas the mixed mode VII cracks, they propagate with a certain angle to form a wing crack at the early stage, and finally they propagate along the major principal stress direction. For mixed mode I/II cracks, the critical mode I SIF increases slightly with the distance to the symmetrical axis, whereas the critical mode II SIF increases largely as compared to the mode I SIF.
机译：高炉开挖可能会引起隧道周围的径向裂缝，这些裂缝可能在附近的采矿活动下引发并传播。为了研究冲击载荷作用下隧道I型和I / II型混合裂纹的动态断裂行为，提出了一个新的大样本，即具有径向裂纹的隧道（TWSRC）。还使用TWSRC样品和落锤冲击测试设备进行了冲击测试。使用TWSRC样本的优势在于，可以将相应的结果直接用于隧道工程实践，并且可以使隧道设计人员提高隧道的动态稳定性并防止隧道的危害。预裂设计在隧道顶板中，并且平行于隧道的对称轴。裂纹与对称轴之间的距离与隧道顶板半径的比值a在0到1的范围内。用应变仪和裂纹扩展仪测量裂纹的萌生时间和裂纹扩展特性。用有限差分商业代码AUTODYN模拟裂纹扩展路径，分析了断裂机理。采用有限元商业代码ABAQUS来计算裂纹动态应力强度因子（DSIF），并采用实验数值方法测量裂纹萌生韧性。结果表明，对于Ⅰ型裂纹，裂纹沿先出现的裂纹方向扩展；而对于VII型混合裂纹，它们以一定角度扩展，在早期形成翼状裂纹，最后沿主裂纹扩展。主应力方向。对于混合模式I / II裂纹，临界模式I SIF随着到对称轴的距离而略有增加，而临界模式II SIF与模式I SIF相比则大幅增加。

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  • 来源
    《Tunnelling and underground space technology》 |2019年第2期|11-21|共11页
  • 作者

    Zhou Lei; Zhu Zheming; Dong Yuqing; Ying Peng; Wang Meng;

  • 作者单位

    Sichuan Univ, Coll Architecture & Environm, MOE Key Lab Deep Underground Sci & Engn, Chengdu 610065, Sichuan, Peoples R China;

    Sichuan Univ, Coll Architecture & Environm, MOE Key Lab Deep Underground Sci & Engn, Chengdu 610065, Sichuan, Peoples R China;

    Sichuan Univ, Coll Architecture & Environm, MOE Key Lab Deep Underground Sci & Engn, Chengdu 610065, Sichuan, Peoples R China;

    Sichuan Univ, Coll Architecture & Environm, MOE Key Lab Deep Underground Sci & Engn, Chengdu 610065, Sichuan, Peoples R China;

    Sichuan Univ, Coll Architecture & Environm, MOE Key Lab Deep Underground Sci & Engn, Chengdu 610065, Sichuan, Peoples R China;

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  • 正文语种 eng
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  • 关键词

    Tunnel; Mixed-mode crack; Impact loading; Numerical simulation; Dynamic initiation toughness;

    机译：隧道;混合模式裂纹;冲击载荷;数值模拟;动态起初韧性;

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