中文摘要：

为了研究细长单桩和多桩在竖向荷载作用下的压曲变形以及非介入性地测量细长桩屈曲引起的土体变形,利用透明土模型试验并结合粒子图像测速（particle image relocimetry,PIV）技术,成功地对不同长宽比以及不同桩数细长桩的屈曲过程进行了试验研究。采用激光照射透明土形成散斑场,并采用单反相机拍摄关心区域的数字图像,利用PIV技术分析图像所获得的位移场。研究结果表明：单桩情况下,桩上下端发生反方向的屈曲变形;多桩条件下,桩下部存在一定的嵌固深度,上部桩身弯曲形式为半个周期的正弦函数;随着长宽比的增加,产生最大横向位移的点不断上移,但是对上半部分桩屈曲变形的范围影响不大;无论在单桩还是多桩条件下,下部土体的水平抗力大于上部土体,从而导致了最大横向位移发生在桩的上半段。

英文摘要：

In order to investigate the buckling of single and multiple slender piles under vertical loading and intrusively measure the soil deformation caused by pile bucking,a experimental study on bluckling of slender piles with different length-width ratios and pile numbers was successfully carried on based on transparent soil model test combining the technology of particle image velocimetry（PIV）.The speckle field was formed by projecting laser to the transparent soil model.Digital images of the region of interest were recorded using a SLR camera.PIV was employed to obtain the generated displacement fields through analyzing the image.The results show that the buckling deformation of slender pile displays the full wave in case of single pile,and half wave in case of multiple piles.The bending mode of upper pile displays sine function in half period.The maximum lateral displacement point goes up with the increasing of the length-width ratio which shows little impact on buckling deformation range of upper pile.No matter in the case of single pile or multiple piles,lateral resistance in lower part is greater than that in upper parts,which leads to location of maximum lateral displacement in upper part.