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为分析砂土中隧道施工条件下管线与土体相互作用的机理,利用室内模型试验,自制模型箱,以江砂为填料,选取高密度聚乙烯管材进行试验。结果表明:在砂土中,与穿既有管线轴线相垂直的下穿隧道施工过程中,管线中间部位主要受下拉效应影响,而上拱效应则支配着管线两侧的变形;管线的存在对土层位移的影响范围约为水平向距管线轴线3倍的直径;随着地层损失量的增大,管线与土层的变形曲率比值逐渐减小,管线的弯矩与应变相应增大;隧道施工条件下管线上覆荷载有增大的趋势,管线中间部位管底土压力逐渐趋于零,管线与土层分离区宽度随着地层损失量的增大逐渐增大并趋于一恒定值;通过对管土相互作用机理的探讨,明确了沉降槽宽度系数i、中心最大沉降量smax以及管线埋深与管径比值H/D等因素对管土相对刚度的影响,基于室内模型试验结果提出了管土相对刚度的计算式。
In order to analyze the mechanism of interaction between pipelines and soil under tunnel construction conditions in sand soil, indoor model test, self-made model box and river sand were used as filler to select high-density polyethylene pipe for testing. The results show that in the sand soil, the middle part of the pipeline is mainly affected by the pull-down effect during the construction of the tunnel crossing the axis perpendicular to the existing pipeline while the arch effect dominates the deformation on both sides of the pipeline. The existence of the pipeline The influence range of soil displacement is about three times the horizontal from the pipeline axis. With the increase of formation loss, the ratio of deformation and curvature of pipeline and soil gradually decreases, and the bending moment and strain of pipeline increase accordingly. Under the condition of construction, the overburden load on the pipeline tends to increase, and the pressure at the bottom of the pipe in the middle part of the pipeline tends to be zero. The width of the separation zone between the pipeline and the soil layer gradually increases and tends to a constant value as the amount of formation loss increases. The interaction between pipe and soil is discussed. The influence of factors such as width of settlement channel i, maximum center of settlement smax, pipe depth and pipe diameter ratio H / D on the relative stiffness of pipe and soil is clarified. Based on the indoor model test results, Calculation formula of relative stiffness of pipe and soil.