冻融条件下桩基侧摩阻力模型试验研究

Experimental Research of Pile Foundation Side Friction Model under Freezing-thawing Condition

基于自制的冻融循环模型桩试验系统,对桩土间土体融沉引起的桩侧摩阻力进行了室内试验,主要研究了不同含水率土体中模型桩在冻结温度分别为-1,-2,-5℃和-10℃时桩侧摩阻力的变化规律。结果表明:桩侧摩阻力在一定范围内随冻结温度降低而增大;桩侧摩阻力随土体含水率的变化而变化且存在一个界限含水率,低于界限含水率时,侧摩阻力随含水率的增大而增大,反之则随含水率的增大而降低。最后,联系温度与含水率对桩侧摩阻力的作用关系,基于荷载传递法,提出了考虑温度影响因子的冻融土体中桩侧摩阻力计算模型,并以沈阳地铁中段DK11+685联络站建设工程为例,对施工过程中的桩基受力情况做了现场监测。数值计算结果与现场监测结果吻合程度较好,验证了所建立本构关系模型的有效性。

Based on the self-made freezing-thawing cycle model pile test system, the indoor experiment about pile side friction caused by sinking soil is conducted. It mainly studied the changing rules of pile side friction of model piles with different water contents at the freezing temperature of - 1, - 2, - 5, - 10℃. The result shows that （ 1 ） the pile side friction increases as the frozen temperature decreases in a range ; （2） the pile side friction varied with the soil moisture content, and there is a water content limit, when the water content of pile soil is less than it, the pile side friction increases as the water content increases, but when the water content is more than it, the pile side friction decreases as the water content increases. Finally, by linking the relation of temperature and water content with pile side friction, the calculation model of pile side friction in freezing-thawing soil considering the effect of temperature is proposed based on the load transfer method. Taking the construction project of the liaison station in mid-section DK11 ＋ 685 of Shenyang subway for example, the pile foundation stress in construction process is monitored on-site. The numerical computing result agrees well with the field monitoring result, thus the validity of the established constitutive model is proven.