冲刷条件下考虑软粘土应力历史的水平向受荷桩承载性能分析

冲刷会带走桥梁基础附近的土体导致桥梁承载力降低。大部分桥梁事故的发生都和冲刷有关，因此评估冲刷对桥梁安全性的影响格外重要。在实际的生产过程中，对桥梁桩基在冲刷条件下稳定性的评估往往是通过简单地移除桩基附近的土体得到的，但是忽略了剩余土体应力历史的改变。实际上，剩余土体在冲刷作用带走其上覆土体时经历了卸荷的过程，从而导致其超固结比增加。本文在使用p-y曲线理论分析水平向受荷桩时考虑了软粘土的应力历史。为了说明应力历史的影响，对传统的p-y曲线进行修正，计算不同冲刷深度下水平向受荷桩的响应，并通过一个案例来比较考虑和未考虑应力历史影响的计算结果。结果表明考虑了应力历史影响后极限土阻力会下降21.8-32.7%，忽略软粘土的应力历史将导致在设计冲刷条件下的水平向受荷桩时偏不保守。

Behavior of Laterally Loaded Piles under Scour Conditions Considering the Stress History of Undrained Soft Clay

Scour can remove soils around bridge foundations and result in reduced bridge capacity. Because most bridge failures have been associated with scour events, it is important to evaluate scour effects on bridge safety. In practice, an evaluation of the performance of bridge piles under scoured conditions is usually achieved by simply removing soils from around the piles while possible changes in stress history of the remaining soils are ignored. In reality, the remaining soils undergo an unloading process when scour removes soils from above the remaining soils. This process increases the overconsolidation ratios of the remaining soils. In this study, the stress history of soft clay was considered in the analysis of laterally loaded piles using the p-y method. To account for the stress history effect, the conventional p-y curves for the soft clay were modified to evaluate the undrained responses of the laterally loaded piles at different scour depths. A case study was used to compare the computed results by considering and ignoring the stress history effect. The results showed that consideration of the stress history effect resulted in a 21.8-32.7% reduction in ultimate soil resistance. Ignoring the stress history of the soft clay led to an unconservative design of the laterally loaded piles under scour conditions.