Abstract: In recent years, due to river sand mining and flood disaster, the local scouring at the bridge site often develops very violently, which is very easy to cause scour damage to the bridge pile foundation in the disaster area. The rapid assessment method of bearing capacity of bridge pile foundations under the coupling effect of scouring and vehicle loads was developed by iterative finite element calculation. Firstly, based on the constitutive curve of concrete, an improved p-y curve that could take into account the scour pit shape and stress history was used to simulate the interaction between the pile foundation and the soil. Subsequently, based on the load displacement curve at the top of the pier, the allowable stress method and the ultimate bending moment method were respectively adopted to calculate the bearing capacity of the bridge pile foundation under the combined effect of scouring and vehicle loads. Finally, the finite element software ABAQUS was used to establish the solid model of single column pile and soil model of bridge substructure to verify the accuracy of the proposed method. The results show that: when the scouring depth is between 0%~33% pile length, the ultimate load value of the bridge pile foundation decreases rapidly. After the scouring depth reaches 33% of the pile length, the downward trend of the ultimate load value slows down and tends to be smooth gradually.

Key words: bridge engineering; pile foundation; numerical modelling; foundation scouring; vehicle loading

摘要： 近年来由于河道采沙以及洪水灾害等原因，桥址处局部冲刷发展非常剧烈，极易对灾害地区的桥梁桩基础造成冲刷破坏。采用有限元迭代计算开发了桥梁桩基在冲刷作用和车辆荷载耦合作用下承载能力的快速评估方法。首先，基于混凝土本构曲线，采用考虑冲刷坑形态及应力历史的改进p-y曲线来模拟桩基与土体的相互作用。随后，基于墩顶处荷载位移曲线分别采用容许应力法和极限弯矩法分别计算在冲刷与车辆荷载共同作用下桥梁桩基的承载能力。最后，采用有限元软件ABAQUS建立了桥梁下部结构单柱墩实体模型和土体模型验证该方法的准确性。结果表明：当冲刷深度为0%~33%桩长时，桥梁桩基极限荷载值急速下降；当冲刷深度大于33%桩长时，极限荷载值下降趋势减缓，渐渐趋于平稳。

关键词: 桥梁工程；桩基础；数值模型；基础冲刷；车辆荷载