【摘要】 针对广大寒区普遍存在的冻胀-融沉影响桩基承载力问题,以清水河大桥灌注桩为例,基于建立的饱和冻土水-热-力三场耦合模型及研发的3G2012软件系统,深入研究了温度变幅、桩和地基土的传导系数、导水系数、回冻时间等因素对其承载力的影响,揭示了其承载的内在热力学机理.结果表明:钻孔灌注桩承载力随温度发生波动变化,冬季桩基的极限承载力近似为夏季的1.2倍;地基的导水系数提高一个数量级,加剧了地基土中的水分迁移及冻胀融沉变形,进而影响桩基承载力;冻土回冻时间对桩基承载力也有较大影响.以上结论为寒区岩土工程的设计与施工提供量化的科学依据.更多还原

【Abstract】 The bearing capacity of pile foundation is severely affected by the changes in seasonally freezing and thawing processes. By using a thermo-hydro-mechanical coupling model for saturation frozen soil and its analysis software 3G2012,the influences of temperature fluctuation,conductivity coefficient,transmissibility coefficient and refreezing time on the bearing capacity of cast-in-place pile in cold regions are studied in this paper,in which the cast-in-place piles in Qingshuihe Bridge are taken as an example. The study achievements reveal the thermo-dynamicsmechanism of the bearing capacity of cast-in-place pile. It is found that 1) bearing capacity shows a fluctuate change with temperature and the ultimate bearing capacity of the pile foundation in winter is about120% as it in summer; 2) when the transmissibility coefficient within subsoil has one order enhanced,the water migration will be more active and the frost heaving and thawing settlement processes will significantly intensify,affecting the pile’s bearing capacity; 3) also,the process of refrozen has some influence on the bearing capacity of the pile. Further study may provide scientific basis for design and construction of projects in cold regions.更多还原