隧道层状围岩各向异性力学特性研究

Study on the Anisotropic Mechanical Properties of Layered Surrounding Rocks in Tunnels

  • 摘要: 为研究层状围岩在不同层理条件下隧道开挖卸荷过程中的宏观各向异性力学特性,基于连续-非连续耦合原理,构建了采用重叠域耦合的三维层状围岩工程卸荷数值模型,验证了重叠域耦合模型在力学信息传递连续性及其相对于传统界面耦合方法的优越性,在此基础上,系统研究了隧道施工中卸荷作用下层状围岩的变形特征和破裂分布规律。结果表明:(1)所建立的连续-非连续重叠域耦合数值模型能够较好地传递力学信息,在应对局部产生应力集中、不连续等问题时,性能优于界面耦合模型;(2)对于不同倾角和倾向的层理面,随着角度增大,层理面边界损伤逐渐加剧;(3)随着层理角度的增大,围岩基质体内破裂由法向拉伸主导逐渐转变为拉-剪复合作用主导,且破裂多聚集于层理界面边缘区域沿层理面向围岩深处蔓延;(4)当层理间距大于3 m时,减小间距会降低围岩完整性,但当间距小于3 m时,围岩稳定性反而增强。

     

    Abstract: In order to study the macroscopic anisotropic mechanical properties of layered tunnel surrounding rock under the influence of different laminar conditions, a three-dimensional numerical model of engineering unloading of layered surrounding rock based on overlapping domain coupling was constructed according to the principle of continuous-discontinuous coupling, and it verified the continuity of the mechanical information transfer of the overlapping domain coupling model and its superiority compared with the interfacial coupling method, and the deformation characteristics and rupture distribution law of layered surrounding rock under the engineering unloading in the course of tunnel construction were investigated. The deformation of layered surrounding rock under the unloading action of the project during the tunnel construction was studied. The results show that: (1) the established continuous-discontinuous overlapping domain coupling numerical model can transfer the mechanical information better, and it is better than the interface coupling model in facing the problems of locally generated stress concentration and discontinuity; (2) for the laminar surfaces with different inclination and inclination, the damage of the boundary of the structural surface is gradually aggravated with the increase of the angle; (3) as the angle of the laminar surfaces increases, the rupture generated in the matrix of the surrounding rock is caused by the normalized rock. (3) As the angle of the laminae increases, the rupture generated in the matrix gradually changes from normal tensile dominance to tensile-shear composite dominance, and mostly gathers in the edge area of the laminae interface to spread along the structural face deeper into the surrounding rock; (4) When the spacing between strata exceeds 3 m, reducing the spacing diminishes rock mass integrity. However, when the spacing falls below 3 m, rock mass stability is paradoxically enhanced.

     

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