柔性基础复合地基的荷载传递规律

Load Transfer Rule of Composite Ground Under Flexible Foundation

引进"典型单元体"与"虚土桩"模型,将柔性基础-垫层-复合地基-下卧层土体视为上下部共同作用的系统,考虑桩土界面之间允许有相对滑移并假设同高度处桩间土沉降不等,改造了Alamgir型桩间土位移模式,得到了柔性基础下复合地基系统的弹性力学微分方程组及其解;通过工程实例验证并评估了该解析解的合理性与精度;最后基于标准算例,通过所得解析解对系统的等沉面高度、中性点位置、桩身轴向应力、桩土应力比等展开了研究。结果表明:该解析解能较准确地反映柔性基础下复合地基的工作性状,沉降计算精度较复合模量法高;系统各因素对荷载传递规律都有不同程度的影响,必须重视系统上下部共同作用的深入研究。

The flexible foundation-cushion-composite ground-underlying strata was considered as an interactive system by bringing in a typical unit model and virtual soil pile model.Considering the relative movement between the pile and soils around the pile,and assuming different settlements at a same original height of soil around the pile,Alamgir displacement mode of soil around the pile was improved.The differential equations of the system were firstly presented and solved.The rationality and precision were verified by an engineering case.On the basis of a standard example,the height of the equal settlement plane,the position of the neutral point,the axial stress of pile,and the pile-soil stress ratio,etc.were studied by the analytical solution.Results show that the analytical solution can accurately reflect the working behavior of the composite ground under a flexible foundation.Calculated settlement precision by the analytical solution is higher than that by the composite modulus method.The factors of the four components of the system can all affect the load transfer rule more or less.It is necessary to pay more attention to the composite ground under the flexible foundation based on super-structure and sub-structure interaction.