基于PIV技术的沉桩过程土体位移场模型试验研究

发布时间：2018-04-08 23:30

本文选题：PIV技术　切入点：模型试验　出处：《工程力学》2014年08期

【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。
[Abstract]:Based on the particle image velocimetry (PIV) technique, the displacement field of soil around the pile was measured by using the self-designed model test system of static pressure pile automatic piling.In the process of piling, CCD(charge coupled device high speed industrial camera was used to continuously photograph the grayscale images of the soil deformation around the pile surface, then the initial point and the peak point were analyzed, and the displacement field distribution was obtained.The effects of pile-soil friction coefficient and pile-tip form on the displacement field of surrounding soil are studied, and the corresponding experimental results are compared with the theoretical solution of circular hole expansion, and the radial displacement and deformation are basically the same.The reliability of the model test is verified.Compared with the conventional test method, the test is easy to operate and does not require high environmental requirements, so it can be used for non-plug-in field measurement.The results show that for circular pile with flat bottom, the influence range of pile-driving process on soil displacement of pile side is near 8R, and that on soil at the end of pile is near 4R.The existence of pile friction increases the influence range of lateral soil displacement by 2R, and has no effect on the soil displacement at the end and bottom of the pile.When the angle of the pile tip changes from 0 掳to 45 掳, the horizontal and vertical displacement of the pile side increases, and the vertical displacement at the bottom of the pile tip decreases obviously, while the friction of the pile body has little effect on the horizontal displacement and the vertical displacement.
【作者单位】：河海大学岩土力学与堤坝工程教育部重点实验室;河海大学土木与交通学院;
【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)
【分类号】：TU435

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