中文摘要：

在已有隧道上方进行基坑开挖,下方隧道的变形是基坑施工控制的关键。采用实测分析的方法,详细介绍了在已建盾构隧道上方进行基坑开挖的工程中,下卧隧道的变形控制措施,即在基坑开挖前进行搅拌桩加固、设置抗拔桩并在隧道内设置＂米＂字型支撑,通过实测数据分析研究了上方基坑开挖过程中下卧隧道的变形规律。得到如下结论 ：搅拌桩加固过程中,隧道发生轻微的下沉变形,而基坑开挖则会导致隧道整体抬升与横截面收敛变形;搅拌桩加固与抗拔桩能有效控制施工过程中的隧道隆起变形,而隧道内的＂米＂字型加固则能有效减小隧道的收敛变形,搅拌桩施工引起隧道发生＂横鸭蛋＂式收敛变形,而后续的基坑开挖则对隧道的收敛变形影响不大。

英文摘要：

To safely excavate a pit over the existing tunnel, it is of great importance to control the deformation of the downside tunnel during the excavation construction process. Measuring analysis method is used in this paper to introduce in detail about the deformation control measures of the lying tunnel in the process of pit excavation.The measures mentioned above include mixing piles strenthening before excavation, setting anti-floating plies and setting ‘star shape＇ support inside the tunnel. Conclusions have been drawn from the analysis of the deformation mechanism of the lying tunnel during pit excavation process：the cement mixing process will cause slight settlement of the tunnel; pit excavation will lead to whole-slab lifting and convergence of the tunnel itself; the cement lifting method and the anti-floating piles can effectively control the uplifting deformation during the tunnel construction process, while the asterisk support inside the tunnel have a strong effort on minimizing the convergence deformation of the tunnel; the construction of mixing piles will cause ‘oval shaped＇ of deformation of the tunnel, while the pit excavation afterwards has little influence on the deformation.