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某拟建立交桥工程桥墩采用桩基础形式,共8处上跨已运营的天津地铁2号线浅埋隧道,立交桥桩与隧道的最小净距为6.5 m。由于土质软弱、桩顶荷载大、桩距隧道近的特点,桩基施工及桩基承担的荷载均将可能对隧道产生影响。建立了三维有限元数值模型,模拟了立交桥桥墩桩基础的成孔施工、运营期桩基承担荷载在土中产生的应力扩散对既有隧道结构和轨道变形产生的影响,分析了单个承台桩基础及考虑多个承台桩基础叠加效应对邻近既有隧道的影响规律,提出了相应的变形控制措施。
A bridge project to be built over the bridge pile foundation form, a total of 8 across the already operating Tianjin Metro Line 2 shallow tunnel, overpass piles and tunnels minimum clearance of 6.5 m. Due to the weak soil, the high load on the pile top and the close proximity of the pile spacing tunnel, the construction of the pile foundation and the load borne by the pile foundation will probably have an impact on the tunnel. A three-dimensional finite element numerical model is established to simulate the pier construction of overpass bridge pier foundation. During the operation period, the stress diffusion caused by the load of the pile foundation in the soil affects the deformation of the existing tunnel structure and the orbit deformation. Foundation and considering the influence law of the superimposed effect of multiple pile foundation on the adjacent existing tunnel, the corresponding deformation control measures are put forward.