To study the feasibility and application effect of the protective techniques for the shield tunnel with wide -range serious unloading of covering soil , combined with the foundation pit engineering with large area and ultra -deep depth above a certain shield tunnel , the implement effect of the adopted protective techniques of tunnel structure for the shield tunnel with seriously insufficient covering soil caused by the foundation pit excavation were analyzed and verified by using two methods of finite element calculation analysis and monitoring data verification .The results showed that under the conditions of seriously insufficient covering soil over the tunnel and extremely poor engineering geological conditions , adopting the pile -board structure combined with the counterweight , grouting reinforcement of soil layer , grouting in the tunnel and other protective techniques could control the floating deformation of the shield tunnel structure under the conditions of little covering soil ef -fectively , with a good protection effect .These protective techniques are safe and feasible , and can be used as the reference basis for the protection work of shield tunnel with similar conditions .%为了研究大范围覆土严重卸载条件下盾构隧道保护技术的可行性及其应用效果,结合某盾构隧道上方大面积超深度基坑工程,采用有限元计算分析及监测数据验证2种方式,对基坑开挖导致盾构隧道上方覆土严重不足,采取的隧道结构保护技术实施效果进行分析和验证.研究结果表明:在隧道上方覆土严重不足、工程地质条件极差等条件下,采用桩板结构,综合隧道内配重、土层注浆加固、洞内注浆等保护技术,能有效控制盾构隧道结构在极小覆土工况下的上浮变形,可取得良好的保护效果,采用的保护技术安全可行,可作为类似工况下盾构隧道保护工作参照依据.
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