考虑卸压孔卸荷作用的人工冻土冻胀特性研究

RESEARCH ON FROST HEAVING CHARACTERISTICS OF ARTIFICIAL FROZEN SOIL BASED ON UNLOADING EFFECT BY DISCHARGE HOLES

  • 摘要: 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。

     

    Abstract: Ground freezing envelope method in foundation pit support and metro tunnel engineering has excellent adaptability and prominent technical advantages in complex geological environmental conditions of special aquifers. As a new geotechnical technique in foundation pit engineering, it depends on artificial refrigeration to freeze aquifer to form curtains. With excellent waterproof, higher rigidity and strength, it is used in unstable soil reinforcement and groundwater insulation. The frost-heaving force is one of the main loads in artificial frozen pit engineering, and the frost force and deformation have great influences on retaining and supporting structures. In application, discharge holes are employed to relieve the frost pressure and deformation. The finite element analysis, experiment and in-situ test show the frozen mechanics and deformation in artificial frozen soil, and may provide theoretical basis for future applications of ground freezing envelope method.

     

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