类矩形盾构施工对地下管线影响的模型试验研究

Model tests on influences of quasi-rectangular shield construction on underground pipelines

类矩形盾构隧道开挖使土体以不均匀沉降形式作用于地下管线,导致管线产生纵向变形、破坏。针对类矩形盾构隧道施工,采用室内缩尺寸模型试验,综合考虑管隧相对位置、管线埋深及土体损失率3个影响因素,研究类矩形盾构隧道在砂土地层中施工,地下管线沉降、变形及地表沉降的规律变化。研究结果表明:管隧垂直工况时,管线竖向位移曲线呈高斯分布,竖线位移反弯点出现在隧道轴线附近处,管线弯矩呈"M"型分布,最大竖向位移及弯矩位于隧道轴线正上方;管隧斜交工况所受影响比管隧垂直工况影响更大;管线埋深越大,管线受影响程度越深;管线竖向位移随土体损失率减小相应降低,隧道轴线正上方管线竖向位移与管线最大正弯矩及两个较大负弯矩减小幅度较大,管线两端受影响程度较小;地表沉降受土体损失影响较大,沉降值比管线大。

Excavation of quasi-rectangular shield tunnels causes uneven settlement of soils in pipelines, resulting in longitudinal deformation and failure of the pipelines. The indoor shrinkage model tests are conducted for the construction of quasi-rectangular shield tunnels. The influencing factors of the relative position of tunnels, buried depth of pipelines and soil loss rate are taken into account. The rules of subsidence, deformation of underground pipelines and surface settlement in dry sand are studied. The results reveal that the vertical displacement curve of the pipelines is Gaussian, the reverse bending point of the vertical displacement appears near the tunnel axis, the bending moment of the pipelines is "M" type distribution, and the maximum vertical displacement and bending moment are located directly above the tunnel axis. The impact of skew conditions of pipelines and tunnels is greater than that of their vertical conditions. The deeper the pipeline is, the larger the influence is.The vertical displacement of the pipelines decreases with the decrease of the soil loss rate. The vertical displacement of the pipelines directly above the tunnel axis and the maximum positive bending moment and two large negative bending moments of the pipelines decrease greatly, and the both sides of the pipelines are less affected. The surface settlement is directly affected by the soil loss, and the settlement value is larger than that of the underground pipelines.