盾构隧道穿越苏州河对防汛墙的影响分析

轨道交通11号线盾构隧道穿越苏州河将会对防汛墙的安全造成影响。为保证盾构顺利实施,拔高影响盾构穿越的桩基,采用双跨门洞式的结构型式对防汛墙结构加固改造。在保证防汛墙安全的前提下,为隧道穿越预留了足够空间。运用有限元数值模拟方法建立计算模型,对隧道穿越前后防汛墙结构的受力和变形形态进行分析。研究结果表明,隧道穿越前底板呈连续梁变形规律,长桩桩身中部和短桩桩端呈向外侧扩张的趋势,整个结构受力性状符合门洞式刚架结构的特性。隧道穿越后,底板的变形趋势与隧道穿越前变形规律相似,最大变形位于隧道上部跨中部位,而桩基变形形态则完全不同,隧道开挖引起长桩桩身中部和短桩桩端向隧道侧的变形,长桩呈挠曲变形,桩身最大变形位于隧道拱轴线附近,短桩呈刚体变形,最大变形位于桩端。经与实测沉降数据对比,盾构的穿越对防汛墙变形的影响处于可控状态,整体防汛墙计算沉降值与实测值较为接近。

Analysis of influence of passing through shield tunnel on flood wall for Suzhou River

The metro 11 line shield tunnel passing through the Suzhou River, will impact on the security of flood wall for Suzhou River. The pile foundation relative to shield tunnel was raised and a “double span” portal frame was adopted to ensure the appliance of shield tunnel. Not only the security of flood wall is assuring, but the space for shield tunnel is adequate to the demand. The diversity in the stress and deformation construction of flood wall with shield tunnel or not, was analyzed by constitutive model built on the finite element method. Before shield tunnelling the deformation of bed plate foundation is consistent in it of continuous beam, both the middle part of long pile and the top part of short pile are detected in the extrorse deformation; and the stress rule of the whole structure accord with inherent characteristic of the portal frame. After shield tunneling the deformation of bed plate foundation is similar to it before shield tunnelling; the maximal deformation lies in the middle part of the tunnel upside. By contraries, after shield tunnelling both the middle part of long pile and the top part of short pile are detected in the introrse deformation. The deformation of long pile is in the form of bending deflection, and the maximal deformation lies in the neighborhood of the tunnel axle wire, the deformation of short pile is in the form of rigid body deformation; the maximal deformation lies in the bottom of itself. The theoretical settlement calculated approximates to the practical settlement tested; it is shown that the influence on the deformation of the flood wall by shield tunnelling is of controllable condition.