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选取青藏高原国道214沿线低温基本稳定区查拉坪旱桥桩基和高温不稳定区花石峡试验场桩基,对其运行期内地温进行连续监测。基于现场地温实测数据,从冻土上限、冻结及融化过程3个方面,分析桩基对冻土地温的影响,显示因桩基良好的导热性能加剧了桩周冻土与大气的热交换,桩周地温年较差明显增大。结合勘察设计资料建立数学模型,应用有限元数值模拟方法就桩基对地温场的长期影响进行预测,结果表明,未来50 a气温上升2℃的情况下,桩侧冻土上限与天然上限差异有所增大,桩侧多年冻土温度升高,该现象在高温不稳定冻土区表现得更为明显。所得结论可为多年冻土区桩基设计、降温保护措施采取及运行管理措施实施提供参考。
Select the pile foundation of Qiaolaping dry bridge and the Huashixia experimental pile foundation in the high temperature unstable region along the low temperature basic stability zone of Qinghai-Tibet Plateau to continuously monitor the ground temperature during its operation period. Based on the measured data of the ground temperature, the influence of the pile foundation on the ground temperature of frozen soil from three aspects of the upper limit of frozen soil, freezing and thawing process is analyzed. It shows that due to the good thermal conductivity of pile foundation, the heat exchange between permafrost and air in pile circumference is exacerbated. Weeks warm years significantly worse. Combined with the survey data, the mathematical model is set up and the long-term influence of pile foundation on the ground temperature field is predicted by finite element method. The results show that there is difference between the upper limit of permafrost and natural upper limit The temperature of the permafrost on the pile increases, and the phenomenon is more obvious in the unstable frozen permafrost region. The conclusions can provide references for design of pile foundation in permafrost region, adoption of cooling protection measures and implementation of operation management measures.