摘要
从波动问题物理本质出发,提取阻抗比和周期比作为表征不同土层条件下场地周期变化规律的基本特征量。提出了子层周期贡献系数的概念,并指出其可由阻抗比和周期比唯一确定,建立了周期贡献系数与阻抗比和周期比一般关系。采用子层周期加权累加方式形成一套简单实用且具有明确物理意义的成层场地基本周期估算方法,以传递函数法结果为标准,就240种工况算例与现有简化方法进行对比,给出各方法偏差分析和适用性评价。主要结论为:阻抗比和周期比作为场地周期研究的基本特征量,结果具有完备性;传统法无法反映土层结构对场地周期的影响,对最普遍的渐硬型场地,偏差也有可能达到40%以上,对存在极端软夹层情况其偏差极易大于20%;Hadjian法精度明显优于传统法,但方法和参数本身缺乏明确的物理意义;新方法在一般和极端两种情况下最大偏差均不超过8%,偏差小于5%和2%工况数占比分别达到85%和60%以上,高于Hadjian简化法,可以在实际工程中推广应用。
Based on the wave motion principle,the impedance ratio and sublayer period ratio were extracted as basic variables to characterize the regularities of fundamental periods under different site conditions.The concept of sublayer contribution coefficient was put forward,which can be definitely determined by the two basic variables selected.Thus,a general relationship among the coefficient,impedance ratio and period ratio was established.A simple and practical method with clear physical significance was proposed to estimate the predominant period of stratified sites by using the sublayer periodic weighted cumulative technique.Taking the transfer function results as standard values,overall comparison of the proposed method with available simplified approaches was carried out under 240 calculation conditions,and the deviation analysis and applicability evaluation of different methods were given accordingly.Results show that the impedance ratio and sublayer period ratio were suitable as characteristic variables for site period research.The traditional method with simple summation of sublayer periods cannot reflect the effect of soil layer structure on the site period.Its relative deviation may reach more than 40% for the most common progressive hardening sites,and the deviations can easily be great than 20% for situations with extreme soft interlayer.Hadjian's method exhibits an obviously higher accuracy than the classical method,while the method itself and its parameters lack clear physical meanings.The maximum relative deviations are always less than 8% for the proposed method under general and extreme situations,and the case proportions with deviation less than 5% and 2% are above 85% and 60% respectively,significantly higher than those of Hadjian's method.The results strongly reveal that the new method fully meets the engineering accuracy requirements,and can be promoted in practical engineering.
作者
李瑞山
袁晓铭
LI Rui-shan;YUAN Xiao-ming(Key Laboratory of Earthquake Engineering and Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin,Heilongjiang 150080,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第8期3227-3235,共9页
Rock and Soil Mechanics
基金
中国地震局工程力学研究所基本科研业务费专项(No.2018B01,No.2018A01)
黑龙江省自然科学基金联合引导项目(No.LH2019E093)~~
关键词
成层场地
基本周期
简化计算方法
周期贡献系数
土层结构
layered soil site
fundamental per iod
simplified calculation method
period contribution coefficient
soil layer structure
作者简介
第一作者:李瑞山,男,1987年生,博士,助理研究员,主要从事土动力学和岩土地震工程研究。E-mail:lrshan22@hotmail.com;通讯作者:袁晓铭,男,1963年生,博士,研究员,博士生导师,主要从事土动力学和岩土地震工程研究。E-mail:yxmiem@126.com.
