Current experimental study on piled emban kments mostly investigates the stress distribution and load transfer, however, the internal displacement of emban kments is difficult to be measured in the test .Therefore, transparent soil model test is conducted to study the soil arching in piled emban kments which makes the visualiza -tion of internal deformation in emban kments .The settlement on the surface of water bag is used to simulate the for-mation of soil arching in emban kments in the test .Moreover , photos in this process can be dealt by particle image velocimetry ( PIV) technique to obtain the displacement distribution of emban kment fill .Test analysis shows that there are no apparent slip plane during deformation , the macroscopic soil arch shape in emban kment is consist of multiple similar arches , each arch of which can be approximated as a semi-ellipse .With the amount of subsidence increasing , the shape of soil arch almost remain unchanged .The deformation of the fill between piles get the maxi-mum value at its center , and this value become smaller with the depth decreasing .The equal settlement plane ap-pears when reach a certain height .When the fill between piles is subsiding , the horizontal planes below equal set-tlement plane gradually become concave shape and is symmetrical to the centerline of soil between piles .When the settlement is large , with the depth increases , the range of fill ’ s deformation become larger .In the area where the roadbed’ s upper deformation is smaller , the distribution of horizontal displacement is similar to symmetrical , and the soil aggregate from the sides to the middle .When the settlement of soil between piles become smaller , these horizontal displacement curves will be more uniform .%目前通过试验研究桩承式路堤时，多是探讨路堤中的应力分布和荷载传递，而路堤内部变形一般在试验中难以准确测量。基于此，利用透明土模型对桩承式路堤中土拱效应进行试验研究，实现了路堤内部变形的可视化。模型试验通过桩间水袋上表面的下移来模拟路堤中土拱的形成过程；并将该过程中获得的照片，经过粒子图像测速（ PIV）技术处理，得出路堤填土的位移分布。试验分析表明：路堤在变形过程中没有明显的滑移面，宏观土拱形态为多个形状相似的拱，每个单拱可近似看作半椭圆；随着桩间土上表面下沉量加大，土拱形态几乎不变。接近桩间土表面中心处土体变形最大，从下往上路堤填土变形逐渐减小，到达一定高度表现出等沉面。桩间土沉降过程中，等沉面以下各水平面逐渐变为下凹形，各水平面沉降对称于桩间土中心线分布。当沉降较大时，随着到路堤顶面的竖向距离加大，填土变形范围越大。路堤上部变形较小的区域，水平向位移近似于对称分布，土体有从两边向中间聚集的趋势。桩间土沉降越小，水平向位移曲线变化越均匀。
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