The pile-supported embankment has been widely adopted in highway widening projects. There is often significant differential settlement between the new and old embankments. Previous studies have not clarified the interaction mechanisms between different parts of the widening subgrade. In this research, a series of centrifuge model tests were carried out on the subgrades widened by pile-supported embankment on the soft soil base. The effect of the old embankment and piles on the subgrade deformation subject to new embankment is analyzed based on the full-field measurement results of displacement. The embankment displacement is mainly vertically downward and basically caused by the deformation of the soft soil base. The old embankment redistributes the vertical deformation of soft soil base by increasing and decreasing the vertical displacement in turn along the direction towards the slope surface. The piles exhibit supporting effect on the embankment above and restrict the vertical movement of the soil base. The piles influence the deformation of soft soil base within a certain area which expands with the increasing number of piles. The boundary of the pile influential area moves towards the subgrade axis with increasing depth. The vertical deformation of soft soil base shows peaks that are nearly linearly distributed along depth in the pile influential area. As the number of piles increases, the verticality degree of such linear distribution changes from the vertical to the slope firstly and then reverts to the vertical.

桩基路堤在公路拓宽工程中得到广泛采用。新旧路堤之间经常存在显着的沉降差异。先前的研究尚未阐明加宽路基不同部分之间的相互作用机制。本研究针对软土地基桩基路堤加宽路基进行了一系列离心机模型试验。根据全场位移实测结果，分析了旧路堤和桩对新路堤路基变形的影响。路堤位移以竖向向下为主，基本由软土地基变形引起。旧路堤通过沿向坡面方向依次增大和减小竖向位移的方式重新分配软土地基的竖向变形。桩对上方路堤起到支撑作用，限制土基的竖向移动。桩对一定范围内软土地基变形的影响随着桩数的增加而扩大。随着深度的增加，桩影响区边界向路基轴线方向移动。软土地基竖向变形在桩影响区沿深度呈现近线性分布的峰值。随着桩数的增加，这种线性分布的垂直度首先从垂直变为斜坡，然后又恢复到垂直。