超大直径盾构隧道下穿铁路施工的离心机模型试验研究

Centrifugal Model Test on Construction Process of a Super Large Diameter Shield Tunnel Passing under Existing Railway

  • 摘要: 盾构隧道近接下穿运营高速铁路施工会引起地基下沉、轨道不均匀沉降等病害,严重影响线路的正常运行,甚至会对铁路造成破坏。为研究超大直径盾构隧道动态掘进过程对地表城际铁路沉降影响,文章以武汉两湖超大直径盾构隧道斜下穿城际铁路项目为依托,通过土工离心机模型试验模拟了超大直径盾构隧道近接下穿城际铁路施工中盾构接近-下穿-驶离铁路的整个动态过程。研究结果表明:(1)盾构掘进对铁路路基的影响主要集中在下穿点前后各25 m范围,距下穿点25 m之外盾构掘进对铁路路基的影响很小;(2)盾构掘进过程中,下穿铁路前由盾构掘进引起的铁路路基沉降约占掘进全过程引起铁路路基总沉降的36%,下穿后约占64%,下穿后铁路路基沉降速率迅速增加,且大于下穿前;(3)以盾构掘进下穿过铁路15 m处为分界点,在此之前在盾构掘进方向左侧的路基沉降大于右侧的路基沉降,在此之后则相反,最终盾构掘进方向右侧的铁路路基沉降大于左侧。

     

    Abstract: The adjacent construction of a shield tunnel passing under operating high-speed railways will cause sub? grade settlement, uneven settlement of the track and other problems, which will affect the normal operation of the railway line and, in serious cases, also cause damage to the railway. In order to study the influence on settlement and settlement pattern of the intercity railways caused by the dynamic construction process of shield tunnels with super large diameters, based on the Wuhan Lianghu shield-driven highway tunnel with super large diameter and obliquely passing under the intercity railway, it simulates the whole dynamic process of the shield machine approaching-passing under-leaving the railway through geotechnical centrifuge model test. The research results show that: (1) the impact of shield tunnelling on the railway subgrade is mainly concentrated in the range of 25 m before and after the under-crossing point, while such impact beyond 25 m from the under-crossing point is quite small; (2) during the shield tunnelling process, the settlement of the railway subgrade caused by the tunnelling before under-crossing accounts for about 36% of the total railway subgrade settlement induced by tunnelling, while the settlement after under-crossing accounts for about 64%, and the settlement rate of the railway subgrade after the under-crossing increases rapidly and is greater than that before under-crossing; (3) taking 15 m where the shield has been passing under the railway as the dividing point, the settlement of the subgrade on the left side in the shield tunnelling direction is greater than that on the right side before the dividing point, and the opposite after, eventually the settlement of the railway subgrade on the right side in the shield tunnelling direction is greater than that on the left side.

     

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