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临近既有隧道冻结法施工影响分析和探究

Proximity to Existing Tunnel Freezing Method Construction Impact Analysis and Exploration

  • 摘要: 为探究冻结法施工对临近既有隧道的影响程度,建立可推广的变形预测方法,亟需揭示冻胀–结构相互作用机制并量化其影响。本文依托佛山市某地铁项目,针对采用冻结法施工的联络通道下穿既有地铁盾构隧道工况,采用三维有限元数值模拟方法,结合土体冻胀效应与隧道结构相互作用机制,分析冻结对既有隧道的变形影响,并基于监测数据对分析模型进行验证,获得冻结法施工对上部盾构隧道结构的影响预测模型,并定量分析施工对上部隧道结构的影响程度。由于冻胀效应明显,对大变形条件下的隧道结构性能进行分析计算,确定变形控制标准。研究结果表明,数值模拟方法能够分析冻结法施工过程对上覆建(构)筑物的影响,预测模型对冻结法施工的全过程预测结果与实测数据结果拟合度较高,误差约2.6%。本研究可为类似工况下变形控制标准的制定与安全评估提供可直接套用的量化依据。

     

    Abstract: In order to investigate the influence of freezing method construction on existing tunnels and establish a general deformation prediction method, it is urgent to reveal the mechanism frost heave-structure interaction and quantify its influence. This paper is based on a certain subway project in Foshan City, which uses the freezing method construction of the contact to under the existing subway shield tunnel engineering condition, and uses the three-dimensional finite element numerical simulation method. The deformation influence of freezing on the existing tunnel is analyzed in combination with frost heave effect of soil and the interaction mechanism between tunnel structure. And based on the monitoring data, the analysis model is verified, and the influence prediction model of the freezing method on the upper shield tunnel structure is obtained. The influence of construction on the upper tunnel structure is quantitatively analyzed. Since the frost heave effect is obvious, the performance of the tunnel under large deformation conditions is quantitatively analyzed and calculated, and the deformation control standard is determined. The results of the study show that the numerical simulation method can analyze the influence of the method construction process on the overlying (structural) buildings, and the prediction model has a high degree of fit with the measured data results for the prediction results of the whole process the freezing method construction, with an error of about 2.6%. This study provides a direct quantitative basis for the formulation of deformation control standards and safety assessment in similar engineering.

     

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