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为了准确分析地铁隧道人工冻结施工过程中的热力学状况,考虑水分迁移和冰水相变耦合影响以及水泥水化热的生成,采用热蠕变本构建立了地铁隧道人工冻结施工的水热力耦合分析模型。对广州地铁某双线隧道施工过程中的热力状况进行了数值模拟,同时应用人工冻土的长期强度对冻结壁安全性进行了评估。分析结果表明:在地铁冻结法施工时,最大主应力沿着冻结管呈环形分布,并且管周围的应力明显偏高;开挖对环形应力场的影响不大,而且与其他施工方法不同,人工冻结法施工引起的地表沉降并不随开挖断面的逐渐扩大而增大,整个施工过程中的最大地表沉量仅为9.1mm,因而人工冻结法施工能有效地控制地表沉降量。
In order to accurately analyze the thermodynamic conditions during subway tunnel artificial freezing construction, considering the influence of water migration and ice-water phase change coupling and the generation of hydration heat of cement, the thermal-creep constitutive model was used to establish the coupling analysis of artificial and freezing construction of metro tunnel model. The thermal status of a two-lane tunnel construction in Guangzhou Metro was numerically simulated and the safety of the frozen wall was evaluated using the long-term strength of the artificial frozen soil. The results show that the maximum principal stress distributes along the frozen pipe annularly and the stress around the pipe is obviously high during the subway freezing construction. The excavation has little effect on the annular stress field, and unlike other construction methods, the artificial Surface subsidence caused by the freezing method construction does not increase with the gradual expansion of the excavation section, and the maximum ground surface settlement during the whole construction process is only 9.1 mm. Therefore, the artificial freezing method can effectively control the ground settlement.