盾构隧道开挖引起既有管线的竖向变形研究

Vertical deflection of the existing pipeline due to shield tunnelling

摘要:

盾构隧道开挖不可避免的引起既有地下管线的竖向变形。论文提出了基于双参数Pasternak地基模型的管线竖向变形计算方法。第一阶段采用Loganathan和Poulos提出的解析方法计算盾构隧道开挖引起的既有管线轴线位置处的土体自由位移场；第二阶段将既有管线视为Pasternak弹性地基上的无限长梁，将土体自由位移施加于管线，推导并求解了管线的平衡微分方程，得到了管线竖向位移和内力的表达式。进一步推导并求解了考虑侧向土体作用时的管线平衡微分方程，得到了更符合实际的管线变形。基于简化弹性空间法获得的地基参数，将Pasternak地基和Winkler地基的解析计算结果与数值计算结果以及工程实例监测数据进行对比验证，证明了Pasternak地基模型的优越性和本文计算方法的有效性。

Abstract:

Shield tunnelling will inevitably lead to the vertical deflection of existing pipelines. Based on a Pasternak-type two-parameter elastic foundation model，a two-stage analytical method for estimating the vertical deflection of existing pipelines is presented in this paper. With respect to the first stage, the Loganathan and Poulos analytical solution is used to estimate the free-soil settlement caused by shield tunnelling at the existing pipeline's position; in the second stage, the free-soil settlement is imposed to the existing pipeline, which is simplified as an infinite beam on a Pasternak foundation. The governing differential equations of the pipe are formulated and analytically solved, and the deflection and internal forces of the pipeline are obtained. The effects of the lateral soil beside the pipe are considered and more reasonable results are obtained. Foundation model parameters are determined by the simplifying elastic continuum method. The superiority of the Pasternak foundation model, compared to Winkler foundation model, is qualified by comparing results with numerical results. The accuracy of the proposed method is verified by a good agreement with the engineering case study.