预制静压桩静动载现场试验分析

Analysis of in-situ static and dynamic load tests for precast static pressure pile

原位试验是获取桩基设计参数和了解桩基力学性能的最客观、最可靠方法。基于现有疲劳机和千斤顶等试验设备,研制了桩顶静载和动载组合加载装置,为现场静、动载试验解决了一个技术性难题。利用该装置对某工程混凝土预制静压桩进行了模拟交通荷载的现场静、动载试验。通过单桩竖向抗压静载试验和动载试验,分析了静动载对桩身轴力分布、桩身侧摩阻力和基桩沉降的影响及其变化规律。试验结果表明:在静动载作用下桩身侧摩阻力的分布规律基本一致,并且随着振动次数的增加,桩身上部侧摩阻力减小、下部略有增加,但动载循环超过 30 万次后,侧摩阻力趋于稳定。

In-situ test is the most objective and reliable method to obtain design parameters of pile foundations and to understand the pile mechanism. Based on the experimental equipment, such as fatigue machine and hoisting jack, we researched a combination equipment of static and dynamic load on pile top, a key problem in the static-dynamic load test of pile has been solved. Static and dynamic load test in the filed of precast static pressure piles have been performed by use of combination equipment of static and dynamic load. Distributive regularities of inner force of pile under static and dynamic load, the change of pile's side resistance, and settlement of piles are analyzed by static and dynamic load test. Test results show that the distributive regularities of side resistance of piles are substantial agreement in the process of static and dynamic load. Lateral friction in soft soil of pile stem upside decreases, and lateral friction in bottom soil layer increases; after three hundred thousand times has been vibrated, the side resistance of piles is without changing.