Assessment of Unsaturated Soil Response Under Large Deformations via Ring Shear Testing

通过环剪试验评估大变形下非饱和土的响应

• 批准号: 0626090
• 负责人: Laureano Hoyos
• 金额: $ 20.9万
• 依托单位: University of Texas at Arlington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-10-01 至 2010-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0626090&HistoricalAwards=false
• 关键词: Assessment; Unsaturated; Soil; Response; Under

Project SummaryTitle: Assessment of unsaturated soil response under large deformations via ring shear testingIn this Award project, a series of suction-controlled ring shear tests will be conducted on several identically prepared specimens of compacted sandy silt and silty clay to investigate several key features of unsaturated soil behavior over a whole range of deformations, including pre-failure and post-failure mobility, peak strength, residual strength, threshold deformation levels triggering loss of matric suction (i.e., menisci failure) and time for post-failure menisci regeneration.Ring shear testing will be accomplished at UT-Arlington, under the direct supervision of PI Hoyos, using a novel ring shear testing apparatus that will be made suitable for testing unsaturated soils under controlled-suction states, over a large range of deformations, via axis-translation technique.Results from this research Award will provide the following: (1) A more reliable assessment of shear strength parameters for the analysis/design of foundations, embankments, subgrades, slopes and earth retaining walls resting on or made of unsaturated soils; (2) A better understanding of the mechanisms governing long-runout landslides triggered by rainfalls, such as the recent slope failures in La Conchita, California; (3) A more accurate identification of threshold strain levels causing considerable decrease in unsaturated soil strength during small-to-large strain shearing; (4) A better assessment of the loss of suction effects (menisci failure) during large-strain shearing, and; (5) A better understanding of the influence of cyclic wetting-drying on stress-strain-strength response of unsaturated soils.The suction-controlled ring shear testing apparatus to be developed herein will be the first of its kind to ever be implemented at any geotechnical research institution in the US, and will constitute a major advancement in the state-of-the-art of unsaturated soil testing. The apparatus will facilitate the early exposure of civil engineering graduates to basic and advanced concepts of soil mechanics for unsaturated soils and its applicability in the analysis and design of geotechnical infrastructure resting on unsaturated ground.This Award will also promote partnerships between UTA and other researchers, practitioners, and private instrument developers, worldwide, who are interested in the advancement of the unsaturated soil mechanics discipline. Potential collaborative efforts have already been devised by PI Hoyos with several colleagues at different universities in the U.S., the E.U., and South America.

项目摘要标题：通过环剪试验评估非饱和土在大变形下的反应在本奖项项目中，将对几个相同制备的压实桑迪粉土和粉质粘土试样进行一系列吸力控制环剪试验，以研究整个变形范围内非饱和土行为的几个关键特征，包括破坏前和破坏后的流动性，峰值强度，残余强度，触发基质吸力损失的阈值变形水平（即，环剪试验将在PI Hoyos的直接监督下在UT-阿灵顿完成，使用一种新型的环剪试验装置，该装置将适用于通过轴平移技术在控制吸力状态下测试大范围变形的非饱和土。该研究奖的结果将提供以下内容：（1）更可靠地评估抗剪强度参数，以分析/设计地基、填土、路基、斜坡及挡土墙，或以非饱和土建造;（2）更深入地了解由地震引发的长时间滑坡的机理，例如最近在加州的La Conchita发生的滑坡;（3）更准确地识别在小到大应变剪切过程中引起非饱和土强度显著降低的阈值应变水平;（4）更好地评估吸力效应的损失（大应变剪切过程中的塑性破坏），以及;（5）进一步了解干湿循环对非饱和土应力-应变-强度响应的影响。在此开发的受控环剪切测试设备将是在美国任何岩土研究机构中首次实施的同类设备，并将构成非饱和土测试的最新技术的一个重大进步。该仪器将促进土木工程专业毕业生早期接触非饱和土的基本和先进的土力学概念及其在非饱和地基上的岩土基础设施分析和设计中的适用性。该奖项还将促进UTA与全球其他研究人员，从业人员和私人仪器开发商之间的合作关系，对非饱和土力学学科的发展感兴趣。PI Hoyos已经与美国不同大学的几位同事设计了潜在的合作努力，欧盟，和南美洲