Effects of Void Redistribution on Liquefaction Flow of Layered Soils

空隙再分布对层状土液化流动的影响

• 批准号: 0070111
• 负责人: Bruce Kutter
• 金额: $ 34.5万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0070111&HistoricalAwards=false
• 关键词: Effects; Void; Redistribution; Liquefaction; Flow

0070111Kutter, Bruce L.The assessment the post-liquefaction shear resistance behavior of soil is widely recognized as a controlling factor in many large remediation projects throughout the country and world. Decisions on whether to proceed with costly ground improvement projects to mitigate liquefaction hazards often hinge on highly uncertain estimations of post-liquefaction shear resistance of the soil. The objective of these research projects is to better understand the sources of uncertainty.One likely source of uncertainty is the lack of procedures to evaluate the effects of void redistribution on the post-liquefaction shear strength. Void redistribution may be associated with accumulation of earthquake induced pore pressures near interfaces between permeable and impermeable soil and by particle intermixing. A program of dynamic centrifuge modeling tests and laboratory triaxial tests are proposed, in collaboration with a proposed program of l-g shaking table tests conducted by Professor Kokusho at Chuo University, Japan, to study this problem. The centrifuge tests, to be conducted on the 9 m centrifuge at UC Davis will include models with multiple layers of contracting permeability.Professor Kokusho of Chuo University, Japan has observed flow failures and the formation of water interlayers beneath impermeable layers even in steeply sloping ground. Water interlayers, an extreme form of void redistribution raise serious questions regarding validity of typical stability calculations. Collaboration with Professor Kokusho will greatly enhance the benefits of this research by allowing comparisons between shaking table and centrifuge tests over a range of testing conditions.The proposed work includes funding to support, train, and provide valuable experience to graduate and undergraduate students. The MESA, MORE and WIE programs at UC Davis have agreed to help recruit a diverse pool of applicants for the undergraduate positions. The opportunities for students to design, conduct and analyze the large-scale experiments and to meet renowned experts from the US and Japan will be an extremely valuable.This project is supported under the 3rd-year competition under NSF 98-36. "US Japan Cooperative Research in Urban Earthquake Disaster Mitigation."

[7011]李建军，李建军。土壤液化后抗剪特性评价是国内外许多大型修复工程中公认的控制因素。是否进行昂贵的地基改善工程以减轻液化危害的决定往往取决于对液化后土壤抗剪能力的高度不确定的估计。这些研究项目的目的是更好地了解不确定性的来源。不确定性的一个可能来源是缺乏评估液化后孔隙再分布对抗剪强度影响的程序。孔隙重新分布可能与地震引起的孔隙压力的积累有关，这些孔隙压力靠近透水和不透水土壤之间的界面，并与颗粒混合有关。为了研究这一问题，提出了动态离心机建模试验和实验室三轴试验方案，并与日本中央大学Kokusho教授提出的l-g振动台试验方案合作。将在加州大学戴维斯分校的9米离心机上进行的离心机测试将包括具有多层收缩渗透性的模型。日本中央大学的Kokusho教授观察到，即使在陡峭的斜坡上，在不透水层下也会出现水流破坏和水夹层的形成。水夹层是孔隙再分配的一种极端形式，它对典型稳定性计算的有效性提出了严重的质疑。与Kokusho教授的合作将大大提高这项研究的好处，因为它允许在一系列测试条件下比较振动台和离心机测试。拟议的工作包括资助、培训和为研究生和本科生提供宝贵的经验。加州大学戴维斯分校的MESA、MORE和WIE项目已经同意为本科职位招募不同类型的申请者。学生将有机会设计、进行和分析大型实验，并与来自美国和日本的知名专家会面，这将是非常宝贵的机会。该项目在NSF 98-36下的第三年竞争中得到支持。“美日城市地震减灾合作研究”。