承压含水层抽水诱发邻近既有隧道变形影响研究

    Influence of pumping from confined aquifers on deformation of adjacent existing tunnels

    • 摘要: 承压含水层抽水会引发渗流场与应力场之间的耦合效应,易对邻近既有隧道造成附加变形,威胁结构安全。因此,准确评估抽水影响范围并揭示其变形作用机制,对保障邻近隧道结构安全具有重要工程意义。采用Plaxis 3D有限元软件建立有限元模型,探究抽水完成后不同位置隧道的变形及位移特性。研究结果显示:抽水完成后,随着埋深的增大,隧道的沉降与水平位移均呈现非单调发展趋势,整体位移量均在含水层与隔水层交界处出现极值;随着距抽水井距离的增大,隧道的沉降逐渐减小,水平位移呈现先增大后减小的趋势;结合地铁隧道变形控制标准,构建位移等值线影响域划分标准,提出了基于临界位移阈值的工程防护区界定标准,为实际工程提供理论指导。

       

      Abstract: The pumping of confined aquifers will cause the coupling effect between seepage field and stress field, which is easy to cause additional deformation to the adjacent existing tunnels and threaten the safety of the structure. Therefore, it is of great engineering significance to accurately evaluate the influence range of pumping and reveal its deformation mechanism to ensure the safety of adjacent tunnel structures. A finite element model is established with Plaxis 3D finite element software to explore the deformation and displacement characteristics of tunnels at different positions after pumping. The results show that after the completion of pumping, with the increase of buried depth, the settlement and horizontal displacement of the tunnel show a non-monotonic development trend, and the overall displacement peaking at the aquifer and the aquiclude. With the increase of the distance from the pumping well, the settlement of the tunnel decreases gradually, and the horizontal displacement increases first and then decreases. Combined with the deformation control standard of subway tunnel, the influence domain division standard of displacement contour is constructed, and the definition standard of engineering protection zone based on critical displacement threshold is proposed, which provides theoretical guidance for practical engineering.

       

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