地铁盾构施工引起的地层位移和地面沉陷及建筑物开裂、损坏等问题已经成为隧道建设者、设计者和施工者最为关心的环境问题与工程问题。近些年来，国内外学者针对盾构施工诱发的地表沉降问题也做了大量的研究，并取得了一定的成果。但是在分析目前已有理论对地表沉降的预测结果时发现，在预测过程中并没有同时考虑开挖隧道周围土体弹塑性变形和土体移动模式对盾尾环形收敛空间形态和大小的影响，导致预测结果与实测结果相比都偏大。文中在随机介质理论预测模型的基础上，利用弹塑性理论的相关知识和对土体移动模式的分析，对盾尾环形收敛空间和地层主要影响角进行了分析计算。取得了如下成果： （1）从理论上解释了盾构推进时的地层变形机理，归纳总结了引起地层损失的主要因素。在此基础上，利用弹塑性理论的相关知识对单孔圆形隧道盾构开挖后的应力-应变状态进行弹塑性理论分析，得到了随机介质理论中考虑了盾尾弹塑性变形的盾尾环形收敛空间计算式。 （2）分析了随机介质理论中地层主要影响角对预测结果的影响，并通过分析盾构过后隧道上覆土体移动模式对地表沉降的影响，结合土体移动焦点理论，得到了盾构施工引起地表沉降预测时主要影响角的确定方法。 （3）使用Matlab计算软件，并编写了随机介质地表沉降预测公式相应的Matlab计算程序，实现了地铁盾构施工诱发的地表沉降的预测。并分析了在盾构施工诱发的地表沉降中，隧道的埋深、隧道半径、断面收敛量、地层主要影响角、盾尾弹塑性变形量、偏心超挖量以及开挖面处的附加压力对地表沉降的影响。 （4）根据文中对盾构过后断面收敛量和地层主要影响角的计算，并结合已有的隧道周围土体的不均匀收敛计算模型，将随机介质预测模型分为两个部分，得到了既可以考虑弹塑性变形的影响，又可以考虑土体移动模式影响的不均匀收敛计算模型。 （5）利用本文所述的方法分别对西安地铁一号线、二号线和三号线某区间段盾构施工段诱发的地表沉降进行了预测，并与实测结果进行了比较。分析可知，理论预测结果与实测结果较符合，故可供工程实际参考。

The strata displacement、ground subsidence、building crack and damages and other issues caused by tunnel construction have become the most concerned problems of environmental and engineering by the tunnel builders, designers and builders . In recent years, domestic and foreign scholars have made a lot of study on the surface subsidence induced by shield construction， also did a lot of research, and achieved certain results. which attained a lot of achievements. But in the present surface subsidence prediction research, most of the studies did not consider the effect of the elastic-plastic deformation and movement mode of excavation tunnel’s surrounding soil on the shape and size of shield tail annular convergence space. Therefore, this paper on the basis of the random medium theory prediction model, using relevant knowledge of elastic-plastic theory and the analysis of soil movement mode, analysised and calculated the convergence space and shield tail ring formation main influencing Angle. Has achieved the following results. Explaining the formation mechanism of deformation when the shield forward theoretically, and summarized the main factor causing formation damage. Based on this, using elastic-plastic theory knowledge analyzed the state of stress and strain on single-hole circular tunnel after shield excavation. Analysis the influence of the random medium theory formation Angle of main on the result of prediction, And through analyzing the influence of casing body moving patterns of tunneling after shield through on surface subsidence, and Combining the theory of soil mass mobile focus, Got the determine method of main influencing Angle in the cohesive soil , which can be used in prediction the surface subsidence cause by shield construction. Using the Matlb software, and write the Matlab calculation program of the random medium surface subsidence prediction formula ,achieved prediction the surface subsidence by subway shield construction.And analyzed the influence of the buried depth of the tunnel, tunnel radius, main influencing Angle , the size of section convergence, the elastic-plastic deformation in shield tail, overbreak volume of eccentric and the additional pressure in excavation face on surface subsidence. According to the calculation of the section convergence after shield through and the calculation of main influencing Angle in this paper,and Combined with the existing calculation model of the non-uniform convergence of tunnel surrounding soils, divided The random medium model into two parts, Obtained the non-uniform convergence calculation model ,which can not only consider the effect of elastic-plastic deformation, but also can consider the affect of soil movement mode. Using The method which described in this article to predict the ground settlement induced by shield construction for xi 'an metro line 1, line 2, line 3, and made a compare with the measured results . Analysis shows that the oretical prediction results is in accordance with the measured results, so it can be used for the engineering practice.