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对于含水土层特殊地质条件下的基坑围护及地铁隧道等地下工程,冻结围护技术具有良好适应能力和突出技术优势,利用人工制冷使土中液相水冻结为固相冰,使含水土层冻结为人工冻土墙帷幕,提高含水土层强度和刚度以及止水隔渗性能,加固不稳定土层和隔绝地下水。但人工冻结围护在工程应用中,冻胀与变形对基坑围护支撑结构和周边环境影响甚大,冻胀力是支撑围护结构的主要荷载之一,而采用卸压孔(槽)的卸荷作用对冻胀的释放和变形的控制具有显著功效。通过对冻结围护工程冻胀性状有限元分析以及卸压孔对冻胀卸荷作用的探讨,结合试验监测成果验证,系统研究冻结围护工程中人工冻土的冻胀与变形及其卸荷作用下的力学性状特征,为人工冻土冻胀性态的认识以及今后冻结围护工程的推广应用提供理论基础。
For the underground engineering such as foundation pit enclosure and subway tunnel under special geological conditions of water-bearing soil, the technology of freezing enclosure has a good adaptability and prominent technical advantages. By artificial refrigeration, liquid water in the soil is frozen into solid-phase ice, Frozen water and soil artificial frozen soil wall curtain to improve the strength and stiffness of water-bearing soil and water and impermeability, reinforcement of unstable soil and isolation of groundwater. However, in the engineering application, the frost heave and deformation have a great influence on the supporting structure of the foundation pit and the surrounding environment. Frost heaving force is one of the main loads supporting the retaining structure, and the pressure relief hole Unloading effect on the release of frost heaving and deformation control has a significant effect. Based on the finite element analysis of the frost heave behavior of the freezing enclosure and the effect of the pressure relief hole on the frost heaving and unloading, the paper studies the test monitoring results to systematically study the frost heave and deformation and the unloading of artificial frozen soil in the freezing enclosure project The mechanical characteristics under the action of this model provide a theoretical basis for the understanding of frost heave behavior of artificial frozen soils and the popularization and application of frozen construction in the future.