土拱效应的形成和荷载传递机制是进行桩承式路堤中桩土相互作用分析的关键性技术问题。为了探究宏观土拱效应形态的演化过程，借助于传统的光弹试验技术，研制出一种直径为3 mm的聚碳酸酯颗粒，通过自制的加载装置和光测力学图像处理系统，实现了桩承式路堤内部应力分布的可视化，直接观测到模型内部力链网格的产生、分布及变化，求得不同高跨比下桩土应力比变化，并与数值模拟的对比分析。结果表明，随着高跨比的减小，土拱形状由三角形变为半圆形，桩土应力比逐渐减小，当填土高度与桩间距的比值 时，可以形成完整的土拱；当 时，土拱效应开始消失。

The formation of soil arching effect and load transfer mechanism are the key technological problems for analyzing pile-soil interaction in piled embankment. In order to research the evolution process of macroscopic soil arching effect morphology, the photoelastic experiment technology is applied and realizing stress visualization in piled embankment model by using a locally developed loading device and optical measurement mechanics image processing system. The rules of generation, distribution and changes of the force network can be directly observed. Then based on comparatively analyzing the pile-soil stress ratio obtained from experiment and finite element numerical simulation, it is shown that the soil arching shape transforms from triangle to semicircle; and pile-soil stress ratio decreases gradually when reducing the height-span ratio. When the ratio of filling height to pile spacing, , is greater than 1, full soil arching is observed; when , the effect of soil arching begins to disappear.