黄土地区通道上跨既有地铁隧道衬砌受力分析

Analysis of Mechanical Characteristics for Lining of Existing Metro Tunnel upper Crossing by Close Range Excavation Passageway in Loess Region

研究目的:为了解黄土地区暗挖通道近距离上跨既有地铁隧道衬砌的受力特征,以西安地铁3号线太白南路站Ⅲ-C至Ⅱ-B间过街通道上跨既有隧道为依托工程,通过现场实测,对既有地铁隧道初支与二衬间接触压力和二衬混凝土应力进行分析研究。研究结论:(1)既有地铁隧道初期支护与二次衬砌间的接触压力先跨线整体比后跨线小,就单洞而言,迎施工面一侧比远离施工面一侧压力大;(2)左、右线各测点接触压力在上跨施工过程中均表现为增大,且后跨线增大幅度大于先跨线;(3)受上跨通道高程多变影响,先跨线二衬产生向左扭转的趋势,左侧受压、右侧先受拉后受压;(4)后跨线二衬应力基本对称,测点应力整体比先跨线大;(5)本研究成果可为黄土地区类似上跨工程的设计和施工提供参考。

Research purposes： In order to understand mechanical characteristics for lining of existing metro tunnel upper crossing by close range excavation passageway in loess region, relied on the project of III- C to II - B passageway of Taibai South Road Station of Xi＇an metro line No. 3, based on the field tests, this paper analyzed the contacting pressure between initial supports and secondary linings and stress of secondary linings of existing metro tunnel.Research conclusions： （ 1 ） The contacting pressure between initial supports and secondary linings of existing metro tunnel in earlier crossing line on the whole is smaller than in later crossing line, and in one tunnel case the pressure on the construction surface side is greater than on the other side. （2） The contacting pressure of each monitoring point in left and right lines is increased in the construction process of upper crossing passageway, and the increase range of monitoring points in later crossing line is more than in the earlier crossing line. （ 3 ） Influenced by the change of upper crossing passageway height, the secondary linings of the earlier crossing line presents the trend twist to the left, the stress of the left side is pressure stress and the right side is first pulling stress after to pressure stress. （4） The stress of secondary linings of later crossing line is basically symmetrical, which on the whole is larger than the earlier crossing line. （5） The research results can provide reference for the design and construction of similar engineering in loess region.