RAPID/Collaborative Research: Investigating the Liquefaction Susceptibility of Calcareous Sand in Hawaii with an Enhanced NHERI@UTexas Large Mobile Shaker

快速/协作研究：使用增强型 NHERI@UTexas 大型移动摇床研究夏威夷钙质砂的液化敏感性

• 批准号: 2317659
• 负责人: Diane Moug
• 金额: $ 7.86万
• 依托单位: Portland State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2317659&HistoricalAwards=false
• 关键词: RAPID; Collaborative; Research; Investigating; Liquefaction

This Grant for Rapid Response Research (RAPID) award supports investigation of the liquefaction hazard of calcareous sands during earthquake shaking. Liquefaction of calcareous sands remains an ongoing challenge, not only in Hawaii where the 2006 Kiholo Bay earthquake caused liquefaction of both dredged and naturally-deposited calcareous soils at the Kawaihae Harbor, but also globally in equatorial regions. The seismic resiliency of infrastructure, including ports, maritime terminals and naval facilities, is a critical component to the economy, emergency response, and security of Hawaii and the US mainland. Calcareous sands differ from quartz sands in several aspects, including intraparticle porosity, abrasive surfaces, crushability, and variable cementation. These unique properties mean that established relationships for evaluating the liquefaction hazard of quartz sands cannot be reliably used for calcareous sands without modifications based on fundamental studies. This research will improve earthquake preparedness of Hawaii and contribute more broadly to a fundamental understanding of this locally abundant material.The specific objectives of this project are: (1) characterize the strain-based liquefaction susceptibility relationship for Hawaii calcareous sand and compare it to established relationships for quartz sands, (2) examine the dependency of the strain-based liquefaction susceptibility relationship on initial soil state and effective stress, and (3) collect site-specific cone penetration tip resistance and shear wave velocity to relate to laboratory-derived cyclic strength. In situ cyclic testing will be performed with the NHERI@UTexas T-Rex mobile shaker to investigate relationships between cyclic shear strain and excess porewater pressure generation below a depth of 2 m. The enhanced shaking at depth will be obtained by applying T-Rex to a helical soil anchor that is installed along with a special array of particle velocity and pore-water-pressure transducers to various depths of interest. Cyclic laboratory testing on site-sampled soil will be used to characterize cyclic behavior of the calcareous sand under an expanded set of conditions and initial states from the in situ testing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该快速响应研究补助金 (RAPID) 奖项支持对地震过程中钙质砂液化危险的调查。钙质砂的液化仍然是一个持续的挑战，不仅在夏威夷（2006 年基霍洛湾地震导致卡瓦伊哈伊港疏浚和自然沉积的钙质土壤液化），而且在全球赤道地区也是如此。港口、海运码头和海军设施等基础设施的抗震能力是夏威夷和美国大陆经济、应急响应和安全的重要组成部分。钙质砂在几个方面与石英砂不同，包括颗粒内孔隙率、磨料表面、可破碎性和可变胶结作用。这些独特的性质意味着，如果不根据基础研究进行修改，则无法将用于评估石英砂液化危险的既定关系可靠地用于钙质砂。这项研究将改善夏威夷的地震准备工作，并有助于更广泛地了解这种当地丰富的材料。该项目的具体目标是：（1）表征夏威夷钙质砂基于应变的液化敏感性关系，并将其与已建立的模型进行比较石英砂的关系，(2) 检查基于应变的液化敏感性关系对初始土壤状态和有效应力的依赖性，(3) 收集特定地点的锥体穿透尖端阻力和剪切波速度，以与实验室导出的相关循环强度。将使用 NHERI@UTexas T-Rex 移动振动台进行原位循环测试，以研究循环剪切应变与 2 m 深度以下的超孔隙水压力生成之间的关系。通过将 T-Rex 应用于螺旋土锚，可以增强深度的振动，该锚与一系列特殊的粒子速度和孔隙水压力传感器一起安装到不同的感兴趣深度。对现场采样土壤进行循环实验室测试将用于表征钙质砂在原位测试的一系列条件和初始状态下的循环行为。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。