摘要
基于粒子图像测速(PIV)技术,利用自行设计的静压桩自动沉桩模型试验系统,对沉桩过程中桩周土体位移场进行测量。在沉桩过程中,利用CCD(charge coupled device)高速工业相机连续拍摄试验观测面上桩周土体变形的灰度图像,然后对初始点和峰值点进行分析,得到位移场分布。研究了不同沉桩深度、桩-土摩擦系数和桩尖形式情况下沉桩对周围土体位移场的影响规律;相应试验结果与圆孔扩张理论解进行对比分析,其径向位移变形的规律基本一致,验证了模型试验的可靠性。相对常规试验方法,该试验操作简便,对环境要求不高,可以进行非插入式全场测量。研究结果表明:在该文试验条件下,对于平底圆桩,沉桩过程对桩侧土体位移影响范围在8R附近,对桩端底部土体影响范围在4R附近;桩身摩擦的存在使得桩侧向土体位移影响范围增大2R左右,对桩端底部土体位移基本没有影响。当桩尖角度由0°变化为45°时,桩侧的水平和竖向位移均增大,桩端底部的竖向位移明显减小;而桩身摩擦对其水平位移和竖向位移影响不大。
A small-scale modeling test system based on particle image velocimetry(PIV) was developed for studying the movement of soil during a pile installation.During the whole process,a charge coupled device(CCD) camera was used to capture images of planar soil deformation.Using PIV,the displacement distributions during a pile installation were then obtained,considering different jacking depths,frictions and pile shoes.The observed displacements were compared with the theoretical predictions of a cavity expansion method,and the law of radical displacements were similar.Thusly,the test system is valid.Comparing with the traditional test methods,it is easy to operate and the non-intrusive technique has a low request to its environments.The test results showed that for a flat-ended pile,its influence zone was 8R around the pile shaft and 4R below the pile tip;when shaft friction was considered,the observed influence radius was 2R larger around the pile shaft but has little effect below the pile tip.Meanwhile,for a pile with a shoe angle of 45°,the displacement around the pile shaft was higher,but the vertical movement below the pile tip was much lower,compared with the flat-ended pile;when shaft friction was considered,the observed displacement was almost identical.
出处
《工程力学》
EI
CSCD
北大核心
2014年第8期168-174,共7页
Engineering Mechanics
基金
国家自然科学基金高铁联合基金项目(U1134207)
国家自然科学基金项目(51278170)
长江学者和创新团队发展计划项目(IRT1125)
关键词
PIV技术
模型试验
沉桩
位移场
非插入
PIV
modeling test
pile installation
displacement
non-intrusively
