摘要
本文根据收集到的30次地震800余例砂土和粉土液化调查资料,采用优化方法建立和改进了砂土和粉土的液化判别式,其中包括应力比比值法、能量法、规范法和简化应力比比值法的液化判别式。文中首次提出液化判别可信度的概念,指出可信度与回判成功率的区别,说明可信度能更恰当地度量液化判别结果的可靠性。文中应用信息熵理论,提出综合评价液化判别式好坏程度的定量指标。应用上述方法研究优化后的液化判别式可靠性发现,它们对砂土液化判别的适用性是好的,对粉土液化判别的适用性是理想的。但应指出,当以烈度表示地震作用强度时,规范法的适用性是好的,并对10—15m深的砂土或粉土的液化判别也是适用的;当以加速度表示地震作用强度时,用规范法判别液化则遇到了困难。本文引进模糊烈度概念,修改了规范法。修改后的规范法能强好地适用于已知地面加速度情况下的液化判别。 一个场址所受到的地震作用强度可用烈度、地面加速度、震级和震中距等指标表示。本文给出的几种液化判别方法分别适用于上述不同情况。
Based on about 800 case histories of sand and silt liquefaction during 30 earthquakes the formulas of liquefaction prediction are established and improved by optimization approach, including the ratio method of stress ratio, the energy method, the Code method and the simplified ratio method of stress ratio. The concept of confidence level is first proposed. The difference between the confidence level and the succesful ratio is pointed out and measurement of the reliability of liquefaction prediction by the confidence level is better than the succesful ratio. According to information theory, a quantitative index is proposed for evaluating comprehensively the reliability of liquefaction prediction. It is found out that the formulas optimized in this paper are good for liquefaction prediction of sand and silt.If the earthquake motion level is described by intensity,the Code method will be good and will be suitable for sands and silts with 10 to 15 meters depth. If the earthquake motion level is described by peak acceleration of ground motion, the liquefaction prediction will be difficult. Here, introducing fuzzy intensity concept into the Code method and the Code method is improved.The improved method is suitable, when the acceleration of ground motion is known.The ground motion level at a site can be described by intensity,acceleration of ground motion or magnitude of earthquake and epicentral distance. The liquefaction prediction methods given in the paper are suitable for the various cases respectively.
出处
《地震工程与工程振动》
CSCD
北大核心
1991年第2期85-96,共12页
Earthquake Engineering and Engineering Dynamics
