Significance of nonlinear soil-structure interaction (SSI) on the seismic performance of micropiles-retrofitted pile foundations

非线性土-结构相互作用（SSI）对微型桩加固桩基抗震性能的意义

• 批准号: 22K04280
• 负责人: Goit Chandra
• 金额: $ 2.66万
• 依托单位: Saitama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2022
• 资助国家: 日本
• 起止时间: 2022-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-22K04280/
• 关键词: 1g model testing; SSI; impedance functions; kinematic responses; Seismic retrofitting; Micropiles; Nonlinear response; Strong motion

Various seismic retrofitting techniques and strategies have been developed and employed over the years to ensure the seismic performance of existing bridges built prior to the revision of seismic design codes. For retrofitting, however, focus is often given to the bridge piers while lesser attention is paid to the foundations. Out of the many reasons for such attention to the foundations, one can be attributed to the relatively lesser-known seismic performance of the retrofitted foundations. Damage seen in 2016 Kumamoto earthquake revealed the failure of a bridge foundation even though the pier of the bridge was seismically retrofitted, highlighting the necessity of seismic retrofitting of foundations. In practice, for foundation retrofitting, micropiles are often preferred over the traditional piles for its several merits. The behavior of micropiles-retrofitted foundations considering the effects of nonlinear soil-structure interaction (SSI) under dynamic loading, however, is still largely unknown.To this end, 1g model testing of micropiles-retrofitted pile foundations embedded in soil is considered under a range of static and dynamic loads. Results are quantified in terms of kinematic interaction factors and lateral pile-head impedance functions. A 1/20 model of retrofitted foundation based on the law of similitude is considered. For soil, dry Gifu sand is selected.

多年来，已经开发和采用了各种地震改造技术和策略，以确保在修订地震设计法规之前建造的现有桥梁的地震性能。但是，对于翻新，通常将重点放在桥墩上，而对基础的关注较少。由于这种关注基础的许多原因，可以归因于相对鲜为人知的改装基础的地震表现。 2016年昆马托地震发生的损害显示了桥梁基础的失败，即使桥的码头进行了地震改造，突出了地震改造地基的必要性。在实践中，对于基础改造，微孔通常比传统桩的几种优点更受欢迎。但是，在动态载荷下非线性土壤结构相互作用（SSI）在动态载荷下的影响（SSI）的影响仍在很大程度上是未知的。为此，在土壤中嵌入的微孔 - 逆转桩基础的1G模型测试在土壤中被认为是静态和动态载荷范围的1G模型测试。结果是根据运动学相互作用因子和侧桩头阻抗功能来量化的。考虑了基于相似定律的1/20改装基础模型。对于土壤，选择干gifu砂。