Abstract The excavation of a new tunnel above an existing shield tunnel at close proximity may cause a series of adverse impacts on the underlying tunnel. Thus, a reasonable assessment of the existing shield tunnel’s responses to overcrossing tunnelling is crucial to ensuring the safety and serviceability of the existing shield tunnel. In this study, a simplified nonlinear analytical method is proposed to rapidly assess existing shield tunnel responses to overcrossing tunnelling. A nonlinear Pasternak foundation model (NPFM), considering the nonlinear deformation of the ground as well as the interaction between adjacent springs and upward tunnel displacement, is proposed for modelling the tunnel-soil interaction associated with unloading stress. An effective Newton’s iterative computational program, combined with the finite difference method, is developed for the nonlinear responses of the existing shield tunnel. The reliability and applicability of the proposed method are subsequently validated by a comparison with the results of three-dimensional finite element analyses and two well-documented and published field measurements. The predictions are also compared with the results of six elastic simplified analytical methods based on different subgrade reaction moduli.

中文翻译：

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使用非线性帕斯捷尔纳克基础模型评估穿越隧道对现有盾构隧道影响的简化分析方法

摘要 紧邻现有盾构隧道上方开挖新隧道可能对下伏隧道造成一系列不利影响。因此，合理评估既有盾构隧道对穿越隧道的响应对于确保既有盾构隧道的安全性和可服务性至关重要。在这项研究中，提出了一种简化的非线性分析方法来快速评估现有的盾构隧道对穿越隧道的响应。考虑到地面的非线性变形以及相邻弹簧和隧道向上位移之间的相互作用，提出了一种非线性 Pasternak 地基模型 (NPFM)，用于模拟与卸载应力相关的隧道-土体相互作用。一个有效的牛顿迭代计算程序，结合有限差分法，是为现有盾构隧道的非线性响应而开发的。随后通过与三维有限元分析的结果和两个有据可查和已发表的现场测量结果进行比较来验证所提出方法的可靠性和适用性。还将预测结果与基于不同路基反应模量的六种弹性简化分析方法的结果进行了比较。