地铁隧道冻结法施工地层三维冻胀融沉的变形机制及预测模型

In the period of subway tunnel construction with freezing method, ground frost heave and thawing settlement can produce serious influence on the surrounding environment. Taking actual tunnel freezing engineering as research background, sample laboratory experiment method is used to obtain thermal physical and mechanical parameters of frozen soil, then experiment results of frost heave and thawing settlement are analyzed for constructing the formulas of three-dimensional frost heave rate and thaw settlement rate according to orthotropic deformation characteristics of frozen soil, through which deformation mechanism of frozen soil three-dimensional frost heave and thawing settlement is revealed. A large raw material model test system is improved, which can simulate subway tunnel freezing construction process, and coupled thermal-stress viscoelastic plastic numerical simulation method of ground three-dimensional frost heave and thawing settlement is proposed. By means of model test, numerical simulation and field measurement, ground three-dimensional freezing temperature field and frost heave and thawing settlement displacement are researched in the period of tunnel construction with freezing method. Using stochastic medium theory, combined with the research results of ground freezing temperature field and frost heave and thawing settlement, duration prediction models of ground three-dimensional frost heave in tunnel freezing period and ground three-dimensional thawing settlement in tunnel thawing period are presented. Research results can provide theoretical basis for tunnel design and construction with artificial freezing method, and have important practical engineering value.

地铁隧道冻结法施工地层的冻胀融沉现象会对工程周边环境产生不良影响，为此，本项目以实际隧道冻结工程为研究背景，采用试样室内试验的方法，获取冻土的热物理力学参数，重点分析冻土三维冻胀融沉试验结果，根据冻土的正交各向异性变形特征，构建冻土三维冻胀率和融沉率的计算公式，揭示冻土三维冻胀融沉的变形机制；改进一套模拟地铁隧道冻结施工全过程的原材料模型试验系统，建立地层三维冻胀融沉的粘弹塑性热力耦合数值模拟方法，采用模型试验、数值模拟和现场实测相结合的方法，研究地铁隧道冻结法施工地层三维冻结温度场和冻胀融沉位移场的分布规律；采用随机介质理论，结合地层冻结温度场和冻胀融沉的研究结果，分别建立隧道冻结期地层三维冻胀变形和隧道解冻期地层三维融沉变形的历时预测模型。研究成果可为地铁隧道人工冻结法的设计和施工提供理论依据，具有重要的工程实用价值。

地铁隧道冻结法施工地层的冻胀融沉现象会对工程周边环境产生不良影响，为此，本项目以实际隧道冻结工程为研究背景，进行冻土热物理力学性能试验，获取冻土热物理力学参数，揭示了冻土三维冻胀融沉变形机制；建立一套可模拟地铁隧道水平冻结法施工的模型试验系统，提出地铁隧道冻结法施工地层三维冻胀变形的热力耦合数值模拟方法，揭示了地铁隧道水平冻结法施工期地层三维冻胀变形规律；研制一套可模拟地铁隧道水平冻结法施工的离心模型试验系统，建立地铁隧道冻结法施工地层三维融沉变形的热力耦合数值模拟方法，揭示了地铁隧道水平冻结法施工期地层三维融沉变形规律；采用地层冻胀融沉变形热力耦合数值模拟方法，揭示了隧道管幕冻结法施工期地层冻胀融沉变形规律，提出了地层冻胀融沉控制技术；考虑土体冻结温度，建立了冻结管管壁恒温条件下的单管冻结温度场解析解，进而采用随机介质理论，建立了地铁隧道冻结期地层三维冻胀变形历时预测模型；考虑冻结壁的温度梯度，建立了地铁隧道自然解冻期地层温度场的解析解，进而采用随机介质理论，建立了地铁隧道自然解冻期地层三维融沉变形历时预测模型。研究成果可为地铁隧道人工冻结法的设计和施工提供理论依据，具有重要的工程实用价值。