Experimental study on the influence of extremely broken surrounding rock grade on the mechanical characteristics of tunnels

IF 3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Physics and Chemistry of the Earth Pub Date : 2024-08-30 DOI:10.1016/j.pce.2024.103718

Yongbin Xie , Xuguang Dong , Xiaoyu Yang , Wangwang Fu , Xin Wang

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Abstract

To study the significant deformation and distortion issues in certain sections of the Qinyu tunnel extremely fragmented surrounding rock under identical conditions, six tunnel sections with the same depth of burial and lithology were selected for on-site monitoring of stress. The experimental data were then used to explore the impact of gradation on the mechanical characteristics of the extremely fragmented surrounding rock tunnels. The results indicate that the tunnel experiences larger stresses at the crown and smaller stresses at the side walls and invert, showing the influence of gradation on the stress behavior of extremely fractured surrounding rock. A dual-fractal structure model was employed to quantitatively describe the gradation of the surrounding rock, yielding fitting coefficients above 0.9. The model demonstrated good applicability for extremely fractured rock with significant particle size differences. Additionally, the relationship between fractal model parameters and the maximum rock pressure at various tunnel sections was discussed, revealing an exponential correlation between the absolute difference in fractal dimensions of coarse and fine particles and the maximum rock pressure. To further understand the factors and the influence of gradation on tunnel rock pressure, indoor model tests were conducted using six different gradations. The experimental results once again confirmed the importance of gradation on the stress behavior of highly fragmented rock tunnels and validated the functional relationship between the absolute difference in fractal dimensions and rock pressure. The results can provide guidance for the design of tunnels with extremely fractured surrounding rocks in the future.

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极破碎围岩等级对隧道力学特性影响的试验研究

为了研究在相同条件下秦屿隧道极破碎围岩某些断面的明显变形和扭曲问题，选取了六个埋深和岩性相同的隧道断面进行现场应力监测。然后利用实验数据探讨了级配对极破碎围岩隧道力学特性的影响。结果表明，隧道顶部的应力较大，而侧壁和反面的应力较小，这表明了分层对极破碎围岩应力行为的影响。采用双分形结构模型来定量描述围岩的分级，拟合系数超过 0.9。该模型对粒径差异明显的极破碎岩石具有良好的适用性。此外，还讨论了分形模型参数与隧道各断面最大岩压之间的关系，发现粗颗粒和细颗粒分形尺寸的绝对差异与最大岩压之间存在指数相关性。为进一步了解分级对隧道岩压的影响因素和影响程度，采用六种不同的分级进行了室内模型试验。实验结果再次证实了分级对高破碎岩隧道应力行为的重要性，并验证了分形尺寸绝对差与岩压之间的函数关系。这些结果可为今后设计围岩极度破碎的隧道提供指导。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Physics and Chemistry of the Earth 地学-地球科学综合

CiteScore

5.40

自引率

2.70%

发文量

176

审稿时长

31.6 weeks

期刊介绍： Physics and Chemistry of the Earth is an international interdisciplinary journal for the rapid publication of collections of refereed communications in separate thematic issues, either stemming from scientific meetings, or, especially compiled for the occasion. There is no restriction on the length of articles published in the journal. Physics and Chemistry of the Earth incorporates the separate Parts A, B and C which existed until the end of 2001. Please note: the Editors are unable to consider submissions that are not invited or linked to a thematic issue. Please do not submit unsolicited papers. The journal covers the following subject areas: -Solid Earth and Geodesy: (geology, geochemistry, tectonophysics, seismology, volcanology, palaeomagnetism and rock magnetism, electromagnetism and potential fields, marine and environmental geosciences as well as geodesy). -Hydrology, Oceans and Atmosphere: (hydrology and water resources research, engineering and management, oceanography and oceanic chemistry, shelf, sea, lake and river sciences, meteorology and atmospheric sciences incl. chemistry as well as climatology and glaciology). -Solar-Terrestrial and Planetary Science: (solar, heliospheric and solar-planetary sciences, geology, geophysics and atmospheric sciences of planets, satellites and small bodies as well as cosmochemistry and exobiology).