在软土地层中,针对小净距盾构隧道施工的地表沉降规律分析,对保证安全施工与控制地表沉降具有重要的意义.以苏州地铁4号线软土地层为例,根据现场条件,设计监测断面,对比单洞与双洞施工的地表沉降的变化规律,并进行分析,得出了以下结论:后行洞施工对先行洞的影响是一个挤压、剪切与拉伸的过程,地表沉降量也随之增减;随着后行洞掌子面向前推进,先行洞地表土体纵、横向沉降量先增大和后减小;先行洞施工后形成的扰动圈,使得后行洞的地表沉降量始终大于先行洞的沉降量.
In the soft soil layer,the analysis of the ground surface settlement in tunnel’s shield construction,it was of great significance to ensure the safe construction and control of ground settlement.Taking the soft soil layer of Suzhou Metro Line 4 as an example,according to the field condition and the monitoring section design,compared with the single hole and double hole construction of surface subsidence’s change law,the following conclusions were drawn: the influence of the tunnel construction of the second hole on the first hole was a process of extrusion,shearing and stretching,and surface subsidence were also increased or reduced;along with the second tunnel’s construction,the first hole’s vertical and lateral settlement of the ground surface increased first and then decreased;after the first hole construction,it formed a disturbance ring,so that the surface settlement of the second tunnel was always greater than the amount of the first hole settlement.
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