【作者】 吴庆；

【导师】 杜守继；

【作者基本信息】 上海交通大学 ， 岩土工程， 2012， 硕士

【摘要】 由于城市基础设施建设的发展和城市地下空间的进一步开发,交通隧道、地下车站等地下构筑物不可避免地变得越来越密集,于是便出现了大量在既有隧道近旁进行加卸载的现象。地面堆载是引起既有盾构隧道变形的重要因素,而地铁隧道过大的纵向和横向变形将导致严重的隧道结构安全问题。本文采用室内模型试验和数值分析方法,并结合上海饱和软土地层中越江隧道大直径、超浅埋的特点,对不同埋深的盾构隧道在不同位置和不同大小的地面堆载作用下的变形规律和变形量进行详细的研究。得到的主要成果如下:(1)无论在正上方还是一侧堆载,堆载的重量一直是影响变形的主要因素,在埋深3.5倍隧道直径以内,堆载量越大,隧道变形越大,而且在堆载的正下方,隧道拱顶垂直附加位移达到最大值。(2)隧道埋深也是重要的因素,隧道埋深变小,地面堆载引起的隧道周围土体的附加应力增大,从而使得既有隧道变形相应增大。埋深3m,堆载20Kpa时隧道变形已经超出容许值,故设定为限制范围;埋深1.5倍隧道直径以内时,堆载对隧道变形的影响比较大,应设定为控制范围和注意范围。(3)堆载位置也是重要的因素,如果堆载位置偏离隧道中线越远,地面堆载引起的隧道周围土体的附加应力减小,从而使得既有隧道变形相应减小;反之堆载位置偏离隧道中线越近,地面堆载引起的隧道周围土体的附加应力增大,从而使得既有隧道变形相应增大。更多还原

【Abstract】 Due to the development of urban infrastructure construction and the further exploitation of urban underground space,underground structures such as traffic tunnel and underground station inevitably become more and more intensive. So there appears a phenomenon that load and unload near the existing tunnel. Ground heaped load is a main factor which causes the deformation of existing shield tunnel. Furthermore, the large longitudinal and transverse deformation of the metro tunnel will lead to serious security problems of the tunnel’s structure.This paper has adopted laboratory model tests as well as numerical analysis to study the deformation rules and deflections of shield tunnels in different burial depths underground heaped load of different positions and magnitudes, taking the characteristics of large diameter and great shallow-buried cross-river tunnels in saturated soft soil layer in Shanghai into consideration. The main achievements are as follows:(1) Whether ground heaped load is over or on the side of the existing tunnel, its magnitude is a main factor which causes the deformation. When the burial depth of the existing tunnel is within 3.5 times the diameter of the tunnel, the larger magnitude of the load is, the larger the deformation of existing shield tunnel will be. What’s more, when the load is over the existing tunnel, the vertical displacement of the arch’s apex reaches maximum length.(2) The burial depth of the existing tunnel is an important factor too. The additional stress of the soil around the existing tunnel becomes larger while the burial depth of the existing tunnel becomes shorter, so the deformation becomes larger accordingly. When the burial depth is 3m and the magnitude of the load is 20Kpa, the tunnel’s deformation has been beyond allow value, so we define it as a limited field?; When the burial depth of the existing tunnel is within 1.5 times the diameter of the tunnel, ground heaped load has an conspicuous effect on the deformation of the existing tunnel, so we define it as a control field and attention field.(3) The load position is an important factor as well. The additional stress of the soil around the existing tunnel becomes smaller while the distance from load position to the centerline of the tunnel becomes longer, so the deformation becomes smaller accordingly. Otherwise the additional stress of the soil around the existing tunnel becomes larger while the distance from load position to the centerline of the tunnel becomes shorter, so the deformation becomes larger accordingly.更多还原