Evaluation of the Bearing Capacity of Scoured Bridge Foundations Using Aluminum Rod Ground Model Tests

Owing to climate change, localized heavy rainfall and typhoons have become increasingly dangerous in recent years, leading to accelerated scour and causing damage to river-crossing bridges supported by shallow foundations. Most studies on bridge scour have mainly aimed to evaluate the ground outflow area from a hydraulic perspective, but only a few have focused on the relationship between such an area and the displacement or residual bearing capacity of the foundation, which is necessary to assess the performance of foundations after flooding events. Our previous study focused on local scour caused by the concentrated removal of ground from the upstream edge of the foundation. This study focuses on internal erosion, where fine soil particles flow out of the layer just beneath the foundation. To evaluate the residual bearing capacity after internal erosion, we conducted vertical loading tests of internally eroded shallow foundations using an aluminum rod ground model from which only the small-diameter aluminum rods were extracted to simulate the phenomenon. The test results showed that: (1) residual settlement occurred immediately after the event causing internal erosion; (2) there was no significant increase in the residual slope angle; and (3) the residual bearing capacity did not decrease during emergency repairs, such as the replenishment of the residual settlement with concrete.