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围岩质量及施工方法是影响隧道超欠挖的本质原因,研究围岩质量与超欠挖的关系,对评价和预测超欠挖、判断隧道结构的稳定性具有重要意义。基于工程实测资料及数值试验,研究了跨度对隧道围岩质量的影响,进而建立了基于多因素评价的围岩质量修正指标。根据隧道开挖断面轮廓具有分形特征的特点,计算了鸳鸯会隧道20个典型断面轮廓分形维数,研究了围岩质量与超欠挖的关系,得出围岩质量多因素修正指标与超挖比及断面轮廓分形维数呈线性关系,随着围岩质量多因素修正指标的提高,超挖比和断面轮廓分形维数将降低,并根据复相关原理,建立了三者间的复相关关系,可为隧道围岩质量的正确评价及超欠挖分析提供有益参考。对比不同围岩分级方法与超欠挖的关系表明,基于多因素评价的BQ法在隧道工程中的适用性更好。
The quality of surrounding rock and its construction method are the essential reasons that influence the overbreak and underbreak of the tunnel. Studying the relationship between the surrounding rock mass and overbreak and underbreak, is of great significance for evaluating and predicting the overbreak and overbreak, and judging the stability of the tunnel structure. Based on the measured data and the numerical experiment, the influence of span on the surrounding rock quality of the tunnel is studied, and the index of rock quality correction based on multi-factor evaluation is established. According to the fractal characteristics of tunnel excavation profile, the fractal dimensions of 20 typical sections of Yuanyanghui tunnel are calculated and the relationship between the surrounding rock mass and over-under-excavation is studied. The multi-factor correction index and over excavation of surrounding rock quality are obtained. And the fractal dimension of profile is linear. With the improvement of the multi-factor correction index of surrounding rock quality, the fractal dimension of over-excavation ratio and profile will decrease. Based on the complex correlation principle, the complex correlation between them , Which can provide a useful reference for the correct evaluation of tunnel surrounding rock mass and analysis of over-under-excavation. The comparison between different grading methods of surrounding rock and over-under-excavation shows that the BQ method based on multi-factor evaluation is more suitable for tunnel engineering.