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，已经开发并采用了各种抗震改造技术和策略，以确保在抗震设计规范修订之前建造的现有桥梁的抗震性能。然而，对于改造来说，往往重点关注桥墩，而较少关注地基。在对地基如此关注的众多原因中，其中一个原因可归因于改造后的地基的抗震性能相对鲜为人知。 2016年熊本地震中，尽管桥墩进行了抗震加固，但桥梁基础仍出现损坏，凸显了基础抗震加固的必要性。在实践中，对于基础改造，微型桩由于其多种优点通常比传统桩更受青睐。然而，考虑动载下非线性土-结构相互作用（SSI）影响的微型桩改造基础的行为仍然很大程度上未知。为此，考虑了埋入土壤中的微型桩改造桩基础的 1g 模型试验。静态和动态负载范围。结果根据运动相互作用因子和横向桩头阻抗函数进行量化。考虑基于相似定律的1/20改造基础模型。土壤选择干燥的岐阜沙。