水平冻结施工浅埋隧道对邻近正交路基的作用分析

Effect of shallow tunnel construction by horizontal freezing on adjacent orthogonal subgrades

为了更合理地评价水平冻结法隧道施工对邻近正交路基的影响,考虑土体的非均匀冻胀性,将路基结构视为弹性的Euler-Bernoulli连续梁,结合变形协调条件并引入随机介质理论和叠加原理,推导得到水平冻结法施工隧道对邻近正交路基作用的耦合计算方程,并编制求解程序;结合工程实例,验证了随机介质预测方法的可靠性,并将实测值与耦合法、两阶段法的计算结果进行对比分析,表明该耦合方法的准确性;最后通过ABAQUS软件进行数值模拟,结果表明:耦合方法与ABAQUS模拟结果整体趋势吻合较好;随着冻结壁逐步扩展,路基同一位置处抬升位移逐渐增大;冷媒介质温度越低、隧道埋深越浅,路基抬升变形越大;位于粉质黏土层中的冻结管对路基抬升变形影响最大。该改进的计算方法可为制定减小水平冻结法隧道施工对路基影响的保护措施提供一定的理论指导。

In order to evaluate the influence of horizontal freezing tunnel construction on the adjacent orthogonal subgrade more reasonably,considering the non-uniform frost heave of soil and regarding the subgrade structure as an elastic Euler Bernoulli continuous beam, a coupling calculation equation for evaluating the effect of horizontal freezing tunnel construction on the adjacent orthogonal subgrade was deduced based on deformation coordination conditions,random medium theory and superposition principle. The reliability of the random medium prediction method was verified by an engineering example,and the accuracy of the coupling method was shown by comparing the measured values with the calculation results of the coupling method and the two-stage method. Finally,numerical simulation was carried out based on ABAQUS software,and the results show that the coupling method and ABAQUS simulation results are in good agreement with each other. It is also shown that the uplift displacement at the same location of the subgrade increases gradually as the frozen wall expands,and that the lower the temperature of the refrigerant medium or the shallower the tunnel depth,the larger the uplift deformation of the subgrade. The frozen pipes in silty clay layers have the greatest impact on the uplift deformation of the subgrade. The improved calculation method in this paper can provide some theoretical guidance for the protection measures to reduce the influence of horizontal freezing tunnel construction on subgrade.