Earthquake Induced Soil Liquefaction: Influence of Temperature and Dissolved Gas

地震引起的土壤液化：温度和溶解气体的影响P.I.：韦恩·A·查理教授，博士，体育，土木工程这项研究的目标是确定温度和溶解气体如何影响1)地震液化的最大距离、严重程度和时间，以及2)引发液化的循环应力比CSR。这项研究将包括详细的文献检索、统计分析、实验室测试程序和理论模型，以确定温度和溶解气体对液化砂土的地震液化和后触发反应的影响。液化层以上常出现地面开裂、地面沉降、侧向扩展和地基破坏等现象。一些研究人员使用了大量的液化案例和实验室测试来1)预测到断层带的距离上限，以及2)导致液化的CSR。然而，文献中没有一项研究将地面温度作为变量。大多数液化的实验室研究都是在室温(约20摄氏度)下进行的，而据报道，地震引起的液化估计地面温度低至约2摄氏度(阿拉斯加)至高达27摄氏度(印度、委内瑞拉和墨西哥)。已知液态水的几个物理性质在此温度范围内会发生变化。P.I.对全球50多次地震进行的有限统计分析表明，较热地区的液化距离是较冷地区的两到三倍。文献还表明，地震引起的液化产生的沙尘和水击要高得多，能量也更大，产生更大的喷沙坑，以及在温暖的气候中比在凉爽的气候中大量逸出的气体。更广泛的影响：这项研究旨在增加对液化的科学理解，并通过将地面温度和溶解气体作为变量来改善当前岩土工程液化分析和预测的最新水平。研究结果将有助于公共安全，提高工程设计和施工的经济性，并教育学生进行地震研究和分析。这些结果还可能影响地震学家(另一个研究领域)进行的地震学研究，他们调查利用古液化进行地震风险研究，并对桩基上的横向扩散和相关的横向压力进行工程研究。研究结果的公布可能会引发大量的现场、实验室和离心机测试和理论建模，以更好地了解这些影响。该提案将培养地震工程领域的研究生，并鼓励本科生和代表性不足的学生参与。智能优点：在评估液化时考虑了许多参数，但温度或溶解气体不在其中。P.I.的初步分析表明，在其他条件相同的情况下，液化可能在较温暖的气候中更为普遍。正因为如此，无论是从理解这一过程的智力价值还是从经济和公共安全的角度来看，温度依赖的想法都是值得追求的。

Earthquake Induced Soil Liquefaction: Influence of Temperature and Dissolved GasP.I.: Professor Wayne A. Charlie, PhD, PE, Civil Eng. Dept., Colorado State UniversityRESEARCH ABSTRACT The objectives of this research are to determine how temperature and dissolved gas influence 1) the maximum distance, severity, and timing of earthquake-induced liquefaction, and 2) the cyclic stress ratio, CSR, inducing liquefaction. The research will include a detailed literature search, statistical analysis, laboratory testing program, and theoretical modeling to determine the influence of temperature and dissolved gases on earthquake-induced liquefaction and post-triggering response of liquefied sandy soil. Ground cracking, ground settlement, lateral spreads and foundation failures commonly occur above liquefied layers. Several investigators have used extensive case histories of liquefaction and laboratory tests to 1) predict upper limits of distance from the zone of faulting, and 2) the CSR inducing liquefaction. However, none of the studies reported in the literature has included ground temperature as a variable. Most laboratory studies of liquefaction have been conducted at room temperature (about 20 degrees C) while earthquake-induced liquefaction has been reported where estimated ground temperatures are as low as about 2 degrees C (Alaska) to as high as 27 degrees C (India, Venezuela and Mexico). Several physical properties of liquid water are known to vary over this temperature range. Limited statistical analysis conducted by the P.I. on over 50 worldwide earthquakes indicates that warmer regions have maximum distances of reported liquefaction two to three times the distances reported in cooler regions. The literature also suggests that earthquake-induced liquefaction produces sand and water blows which are much higher and more energetic, larger sand blow craters, and gases which escapes in larger quantities in warmer climates than in cooler climates. Broader Impacts: The research is designed to increase the scientific understanding of liquefaction and to improve the current Geotechnical Engineering state-of-the-art of liquefaction analysis and prediction by including ground temperature and dissolved gas as variables. The results should contribute to public safety, improvement in economy of engineering design and construction, and educate students in earthquake research and analysis. The results may also impact seismological studies conducted by seismologists (a different field of research) who investigate the use of paleoliquefaction for seismic risk studies and engineering studies of lateral spread and associated lateral pressures on pile foundations. Publication of the research results may trigger substantial field, lab, and centrifuge testing and theoretical modeling to better understand these effects. The proposal will train graduate students in the area of earthquake engineering and undergraduate and underrepresented students will be encouraged to participate. Intellectual Merit: Many parameters have been considered in evaluating liquefaction, but temperature or dissolved gas have not been among them. Preliminary analysis by the P.I. suggests that, other things being equal, liquefaction may be more widespread in warmer climes. Because of this, the idea of temperature dependence is worth pursuing both from an intellectual merit to understand the process and from economic and public safety standpoints.