摘要
现有研究采用荷载传递法时均未计算桩体自重,若直接应用于国内软土地区超长桩基的沉降计算,其精度难以满足高速铁路线下工程严格的沉降控制要求。基于佐藤·悟双折线模型提出侧阻荷载传递函数的假定模式,引入桩体自重并对荷载传递法的基本微分方程进行修正和求解,结合降水引起的桩周土体沉降计算和基于端阻弹性模型的桩端土体沉降计算,获得地下水位变化诱发的基桩沉降计算方法;采用理论推导的基桩沉降解析解,并借助嵌入荷载传递函数的有限元方法,分别对单纯桩顶荷载作用和桩顶荷载与降水共同作用两种工况下的桩侧摩阻力、桩体轴力和基桩沉降进行算例对比分析;有限元计算因考虑了由桩体沉降产生的桩周土体附加竖向位移而与理论计算略有偏差,但两种方法计算结果的变化规律基本一致,验证了降水引起的基桩沉降理论计算公式的合理性及正确性。
The current load transfer method does not consider the weight of pile shaft itself. When it is directly applied to calculating the settlement of super-long pile in the soft soil area, the computational accuracy can hardly meet the requirements of strict control criteria for post-construction settlement of high-speed railway. This paper considers the settlement calculation of both soil around pile due to dewatering and soil beneath pile tip using tip-resistance elastic model. The calculation method of dewatering-induced foundation pile settlement is proposed by modifying and solving the basic differential equation of load transfer method. The weight of pile shaft is combined. A hypothetic load transfer function of skin friction is included using Kedzi’s model. A case study is given. The theoretical solution and the FEM embedded with the hypothetic load transfer function are used. The skin friction, the shaft axial force and the foundation pile settlement are comparatively analyzed under either the action of upper load or the combined loading of upper load and dewatering. The additional vertical displacement of soil around pile due to foundation pile settlement is obtained using both the FEM and the theoretical calculations. The two results have slight difference. The rationality and correctness of the theoretical calculation are verified since its corresponding laws change almost in the same way as those of FEM.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2015年第1期68-74,82,共8页
Rock and Soil Mechanics
基金
中央高校基本科研业务费专项资金资助项目(No.10120110059)
关键词
桩基
降水
负摩阻力
基桩沉降
荷载传递法
pile foundation
dewatering
negative skin friction
foundation pile settlement
load transfer method
