中文摘要：

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。和土体泊松比u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地表附加水平应力盯。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。

英文摘要：

To reveal the distribution of ground displacement and stress caused by the excavation of a shallow-bur- ied shield tunnel in a compound stratum, the equivalent layer method was applied to simplify the prob- lem into a solution for the displacement and stress distribution in a homogeneous formation. Using the modified Lo-ganathan＇ s formula, the expressions of ground displacement and strain component and stress component were de- duced, and a displacement field distribution prediction model was established. Based on a theoretical prediction model, the predicted and measured values were compared, and the effects of elasticity modulus ratio n of the upper and lower soil layers, the depth of tunnel z and the Poisson ratio μ on tunnel excavation are also discussed. As for a tunnel excavation in a soft interbed stratum, the equivalent thickness K of the soft interbed stratum is introduced. The research results show that： 1） with an increase of the n value, the maximum surface settlement S maximum ad- ditional horizontal stress o＇~ and vertical stress σz decrease; 2） with an increase of the z value, the maximum settle- ment increases; 3） with an increase of the μ value, the Smax value decreases and the maximum additional horizontal stress and vertical stress increase; 4） with an increase of the K value, the Smax value increases; and 5） during tunnel construction, displacement and stress diffusion occur in the stratum that is hard at the upper part and soft at the low- er part, while displacement and stress concentration occur in the stratum that is soft at the upper part and hard at the lower part.