水利工程中PC管桩复合地基应用设计分析

Design and Research on Pre-Stressed Concrete Pipe Pile Technique in Hydraulic Engineering

基于软土地基的特性及预应力混凝土管桩复合地基设计相关理论,给出了水利工程中PC管桩复合地基设计特点及具体设计思路,结合实际案例,采用三维非线性有限元"桩-土"模型,通过理论分析与数值模拟探究其应用机理,得出褥垫层最大沉降为8.2 cm、底板最大沉降为9.5 cm,说明褥垫层及底板可大大增加PC管桩实际承载能力,对桩体起到了保护及分担荷载的作用,突破了常规PC管桩复合地基过分依赖桩承担垂直荷载和水平荷载的传统思想。基于数值分析结果可看出,复合地基竖向承载力特征值为202 k Pa,地基处理已达到要求,因此软体地基上的预应力混凝土管桩复合地基应用是可行的;褥垫层、管桩及周围地基土组成了一个复杂的多维应力场,各部件之间相互影响,其中褥垫层与管桩作为加固处理区,大大提升了周围土体的承载力,褥垫层有力调整了上部结构的荷载,使地基承载力得到了更大的扩充。

The research was based on soft soil foundation characteristic and related design theory of pre - stressed concrete （PC） pipe pile composite foundation. The design characteristics and the ideas of the composite foundation of PC pile were given in water conservancy pro- ject. One practical project was analyzed and the ＂pile - soil＂ three - dimensional nonlinear finite element model was established. The appli- cation mechanism was detected by combining theoretical analysis with numerical simulation. The largest displacement amounts of cushion lay- er and floor were $. 2 cm and 9.5cm respectively. It was concluded that the practical bearing capacity of PC pipe pile composite foundation was enhanced by cushion layer and floor which played a role of protecting and sharing load. The original idea was broken that vertical and horizontal load were all undertaken by pile. It can be seen from the analysis results that the value of vertical bearing capacity is 202 kPa and the request of foundation treatment is satisfied. Therefore, the PC pipe pile application of soft soil foundation is feasible. Cushion layer, pile and around foundation soil compose a complex multi - dimension stress field. These structures affect and disturb each other. As the reinforce- ment area, cushion layer and pile enhance the bearing capacity of around soil. The upper structure load is adjusted by cushion layer and the foundation bearing capacity is enlarged.