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徐敬民, 章定文, 刘松玉. 地表框架结构作用下隧道施工诱发的砂质地层变形[J]. 岩土工程学报, 2022, 44(4): 602-612. DOI: 10.11779/CJGE202204002
引用本文: 徐敬民, 章定文, 刘松玉. 地表框架结构作用下隧道施工诱发的砂质地层变形[J]. 岩土工程学报, 2022, 44(4): 602-612. DOI: 10.11779/CJGE202204002
XU Jing-min, ZHANG Ding-wen, LIU Song-yu. Tunneling-induced sandy ground deformation affected by surface framed structures[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(4): 602-612. DOI: 10.11779/CJGE202204002
Citation: XU Jing-min, ZHANG Ding-wen, LIU Song-yu. Tunneling-induced sandy ground deformation affected by surface framed structures[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(4): 602-612. DOI: 10.11779/CJGE202204002

地表框架结构作用下隧道施工诱发的砂质地层变形

Tunneling-induced sandy ground deformation affected by surface framed structures

  • 摘要: 城市地铁隧道施工不可避免的引起地层移动与变形,其运移规律不仅由施工状况和地层条件决定,还会受到临近结构物的影响。通过24组离心模型试验,研究地表筏板基础框架结构对隧道施工引起砂质地层移动与变形规律的影响。试验中采用了建筑的长度、隔间宽度、构件厚度和楼层数量各不相同的5种铝制框架结构,并考虑砂土密度、建筑附加荷载、结构与隧道相对水平位置的影响。通过粒子图像测速技术测量地层与建筑的位移,并揭示了地表沉降与水平移动、土层移动、剪切应变和体积应变的等值线变化规律。研究结果表明,地表框架结构显著影响地层水平移动,位于隧道上方的长建筑可显著限制浅部土层的水平移动,影响程度与建筑荷载、筏板与地表土层间隙大小关联;但偏心的短建筑则会增加土层的水平移动。建筑结构荷载增大土层沉降范围,且影响程度随荷载增加而增大。筏板对地层水平移动的约束导致筏板下方浅部土层中出现剪切带,减轻了土层的收缩变形程度。砂土相对膨胀指数取决于相对密度和应力状态,松散砂土地层表现出整体收缩响应,密砂地层体积变形随隧道体积损失率的增加从收缩逐渐转变为膨胀变形,而建筑的附加荷载轻微增加地层的收缩变形。研究成果可为城市地铁隧道施工对邻近建筑物安全评估和风险管控提供参考依据。

     

    Abstract: The construction of urban subway tunnels will inevitably lead to ground movements and deformations, which are determined by the construction method and strata conditions and affected by the adjacent structures. Based on 24 centrifuge model tests, the influences of frame structures with raft foundations on the movement and deformation of dry sandy ground caused by tunnel construction are studied. Five aluminum frame structure models are manufactured, in which the length of the buildings, the width of the bays, the thickness of building elements and the number of stories are different. The influences of sand density, additional load of buildings and the relative horizontal position of structures and tunnel are considered in the tests. In the centrifugal tests, the displacement data of the soil and buildings are captured by particle image velocimetry technique. The horizontal and vertical displacements of the surface soil, the movements of ground and the contour of shear and volumetric strains are released. The results show that the surface frame structures have a great influence on the horizontal movement of the soil, the central long buildings significantly restrict the horizontal movement of the shallow soil, and the degree of restriction is related to the building load and the size of the gap between rafts and ground surface, while the eccentric short buildings increase the horizontal movement. The structural load widens the ground settlement field, and the degree of influence increases with the increase of building load. The restriction of the foundation to the horizontal movements of soil generally results in a thin shear band at the soil-foundation interface with a decreased maximum contraction level. The relative expansion index of sand depends on the relative density and stress state. Therefore, for the loose soil tests, the loose sand exhibits a contractive response, whereas the dense soil transforms from contractive at lower values of tunnel volume losses towards dilative at higher tunnel volume losses. The building load slightly increases the contractive deformation of the soil. The research results may provide important reference for safety assessment of nearby buildings and risk control of shield tunnel construction in urban areas.

     

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