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纵向变形曲线是隧道开挖面空间约束效应的直观反映,多数纵向变形曲线的研究并未考虑围岩质量和应力水平的影响。基于广义Hoek-Brown准则,采用有限差分法,提出了能够量化不同围岩质量及应力水平下开挖面空间效应差异的纵向变形曲线函数表达式,可以简便地得到不同地质条件下的隧道纵向变形曲线,通过误差分析及与已有研究成果对比,验证了该方法的合理性与普适性。研究结果表明:围岩基本质量指标值相同时,围岩纵向变形曲线随着埋深增加变得更加平缓,即围岩应力及位移的释放过程越缓慢,埋深相同时,随着围岩基本质量指标值的降低,围岩纵向变形曲线显示出同样的趋势,相对于开挖面前方,开挖面后方纵向变形曲线的这种特点更加明显;开挖面处纵向变形也是围岩质量与应力水平的函数,最大值不超过隧道径向变形最终值的30%。
The longitudinal deformation curve is an intuitive reflection of the space constraint effect of the tunnel excavation face. Most of the longitudinal deformation curves do not consider the influence of the surrounding rock mass and stress level. Based on the generalized Hoek-Brown criterion, the longitudinal deformation curve function expression that can quantify the spatial effect difference of excavation surface under different rock mass quality and stress level is proposed by the finite difference method. The longitudinal deformation of the tunnel under different geological conditions can be easily obtained Curve, through the error analysis and comparison with the existing research results, the rationality and universality of this method are verified. The results show that the longitudinal deformation curve of surrounding rock becomes more gentle with the increase of burial depth, that is, the slower the release process of stress and displacement of surrounding rock and the same depth of buried rock, The longitudinal deformation curve of the surrounding rock shows the same trend with the decrease of the quality index value. Compared with the front of the excavation face, the longitudinal deformation curve of the excavation face is more obvious. The longitudinal deformation of the excavation face is also the quality and stress of the surrounding rock Horizontal function, the maximum value does not exceed 30% of the final value of the radial deformation of the tunnel.