复合地层中浅埋盾构隧道开挖引起的地层位移及应力预测分析

发布时间：2019-05-22 02:07

【摘要】：为揭示复合地层中浅埋盾构隧道开挖引起的地层位移及应力,文章基于Покровский当层法,将该问题等效为求解均质地层位移及应力分布问题,结合Loganathan修正公式,推导了复合地层中浅埋盾构隧道开挖引起的地层位移、应变和应力分量表达式,构建了地层位移场分布预测模型。同时基于理论预测模型,对比分析了工程实例的预测位移与实测数据的差别,讨论了上下层土体弹性模量比n、地层深度z和土体泊松比μ对隧道开挖的影响;在分析含软弱夹层隧道开挖问题时,提出了软弱夹层等效厚度K的概念。研究结果表明:随着n的增加,地表最大沉降值Smax、地表附加水平应力σx和竖向应力σz的最大值均有所减小;随着z的增加,地层最大沉降值有所增大;随着μ的增加,Smax有所减小,地表附加水平拉应力σx和竖向应力σz的最大值有所增加;当软弱夹层等效厚度K增加,Smax有所增加;隧道施工时,上硬下软地层产生位移及应力扩散现象,上软下硬地层产生位移及应力集中现象。
[Abstract]:In order to reveal the displacement and stress caused by shallow shield tunnel excavation in composite strata, based on the layer method, the problem is equivalent to solving the displacement and stress distribution problem of homogeneous strata, and the modified formula of Loganathan is combined with the modified formula. The expressions of displacement, strain and stress components caused by shallow shield tunnel excavation in composite strata are derived, and the prediction model of formation displacement field distribution is constructed. At the same time, based on the theoretical prediction model, the difference between the predicted displacement of engineering examples and the measured data is compared and analyzed, and the effects of elastic modulus ratio n, formation depth z and soil Poisson's ratio 渭 on tunnel excavation are discussed. In this paper, the concept of equivalent thickness K of weak interlayer is put forward when analyzing the excavation problem of tunnel with weak interlayer. The results show that the maximum subsidence value of Smax, decreases with the increase of n, and the maximum subsidence value of the formation increases with the increase of z, and the maximum horizontal stress and vertical stress of the surface decrease with the increase of z, and the maximum subsidence value of the formation increases with the increase of z, and the maximum settlement value of the formation increases with the increase of z. With the increase of 渭, Smax decreases, the maximum values of additional horizontal tensile stress 蟽 x and vertical stress 蟽 z increase, and Smax increases with the increase of equivalent thickness K of weak interlayer. During tunnel construction, displacement and stress diffusion occur in the upper and lower soft strata, and displacement and stress concentration occur in the upper and lower soft strata.
【作者单位】：中南大学土木工程学院;中南大学高速铁路建造技术国家工程试验室;
【基金】：国家自然科学基金资助项目(51578550,51538009) 中南大学研究生自主探索创新项目(2017zzts153)
【分类号】：U455.43

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