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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。
Based on the particle image velocimetry (PIV) technique, the displacement field of the soil around the pile during pile driving is measured by using the self-designed static pile driving pile driving model test system. In the process of pile sinking, the grayscale image of the soil around the pile on the experimental observation surface was continuously photographed by CCD (charge coupled device) high-speed industrial camera. Then, the initial and peak points were analyzed to obtain the displacement field distribution. The influence law of pile displacement on the displacement field of surrounding soil under different pile sinking depth, pile-soil friction coefficient and pile tip form is studied. The comparative analysis between the corresponding test results and theoretical solution of circular hole expansion shows that the law of radial displacement deformation Basically the same, verified the reliability of the model test. Relative to the conventional test method, the test is simple and easy to operate and has low environmental requirements. It can perform non-plug-in audience measurement. The results show that under the experimental conditions, the influence range of pile-side soil displacement is about 8R for the flat-bottomed circular pile and pile-sinking course, and around 4R for the bottom soil. The friction of the pile makes the pile Lateral soil displacement range of influence increased about 2R, the bottom of the pile tip soil displacement basically no effect. When the angle of pile tip is changed from 0 ° to 45 °, the horizontal and vertical displacements on pile side increase and the vertical displacement on pile bottom decreases obviously. However, the effect of pile friction on horizontal displacement and vertical displacement is not affected Big.