【摘要】 城市立交隧道施工的难点在于两条隧道合并为一条隧道的交叉口施工,该处存在特大断面隧道、偏连拱隧道和小净距隧道型式的多重转换,施工风险高,对工法、工艺要求苛刻。文章以杭州市紫之隧道的地下立交交叉口工程为依托,提出了一种小洞开大洞,然后再横向开挖,最后反向开挖的施工方法和施工工序。结合工程特点,采用有限元数值模拟和监控量测方法验证了该施工方法的合理性。结果表明:对隧道交叉口采用导洞爬坡反向施工方法可以保证分叉段施工安全,解决小洞往大洞方向开挖的难题;分叉隧道开挖过程中,围岩所受拉应力主要集中在拱顶、拱底及中间岩柱上,所受压应力主要集中在中间岩柱及大拱拱腰、小净距外侧拱腰处;衬砌结构最大拉应力出现在拱底,最大压应力发生在拱腰处。更多还原

【Abstract】 The construction difficulty of an urban underground interchange tunnel is focused on the intersection where two tunnel tubes are incorporated into one-tube tunnel,so the construction is of high risks and the requirements for construction method and technology are rigorous due to multiple conversion of tunnel system modes,such as the super-large section tunnel,the double-arch tunnel and the small-spacing tunnel.Based on construction practice of the underground intersection of Zizhi tunnel in Hangzhou,a construction method and procedure were proposed,namely constructing the large tube from the small tube,then transverse enlarging excavation and finally reverse excavation.The rationality of the proposed construction method was verified by using FEM numerical simulation and monitoring and measuring considering the characteristics of the project.The results show that the construction method of climbing excavation of the adit+transverse enlarging excavation+reverse construction can guarantee the construction safety of tunnel intersection,solve the difficulty excavating from a small tube to a large one;during the construction of the bifurcated tunnel,the tensile stress of surrounding rocks mainly concentrates on the vault,arch bottom and middle rock pillar while the compressive stress mainly concentrates on the middle rock pillar,the haunch of the large arch tunnel and the haunch outside of the small-spacing tunnel;the maximum tensile stress of the lining structure occurs at arch bottom and the maximum compressive stress occurs at haunch.更多还原