摘要
针对软弱夹层受震液化对深厚覆盖层场地振动特性的改变以及其上高土石坝的地震响应影响开展研究。将含有软弱夹层的深厚覆盖层场地简化为三质点体系,推导了软弱夹层液化后的场地卓越周期计算公式,进而分析了液化层特征量对场地卓越周期及场地反应谱的影响规律;应用剪切楔法研究了软弱夹层液化对深厚覆盖层上土石坝坝顶加速度放大系数的影响规律。结果表明:夹层发生液化使得场地卓越周期增大,增大程度与夹层液化程度、上覆层与液化层厚度比λ1、液化层与下卧层厚度比λ2密切相关;液化使得场地类别至少增加一类;液化后场地反应谱呈现短周期减震、长周期加震现象,加震减震的分界线一般在0.61⁃0.88 s范围内,反应谱平台段加宽;液化使得覆盖层上高土石坝坝顶加速度放大系数明显增大,放大作用随着软弱夹层液化程度的增加呈现下降的趋势,在夹层较厚且重度液化时,液化现象对覆盖层上高土石坝动力响应反而有消弱作用。
This paper investigates the influence of liquefaction of the weak interlayer on the vibration characteristics of the deep overburden and the seismic response of the high earth-rock dam.Initially,the deep overburden site with liquefiable interlayer is sim⁃plified into a three-particle system and the calculation formula of predominant period of site after liquefaction of soft interlayer is de⁃rived.Furthermore,the effects of the characteristic parameters of the liquefiable interlayer on the site predominant period and the response spectrum of the site are analyzed.Then,the effect of liquefaction of soft interlayer on acceleration amplification factor of the earth-rock dam on deep overburden is studied by shear wedge method.The results show that the liquification of the interlayer in⁃creases the site predominant period,and the degree of this increase is mainly related to the degree of softening of the liquefiable lay⁃er,the ratio of the overburden layer thickness to the thickness of the liquefiable layerλ1 and the ratio of the liquefiable layer thick⁃ness to the thickness of the substratum layerλ2.Liquefaction adds at least one class to the site category.The surface acceleration spectrum after liquefaction presents the phenomenon that the short-period of the acceleration spectrum decreases while the long-pe⁃riod increases,the division line between increasing and decreasing is generally 0.6-0.9 s,and the platform section of the response spectrum is widened.Liquefaction makes acceleration amplification factor of the high earth-rock dam on overburden obviously in⁃crease,and the magnification decreases with the increase of degree of softening of the liquefiable layer.When the interlayer is thick and heavily liquefied,the seismic response is weaker than that before liquefaction.
作者
刘升欢
宋志强
王飞
刘云贺
刘琛
LIU Sheng-huan;SONG Zhi-qiang;WANG Fei;LIU Yun-he;LIU Chen(State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China,Xi´an University of Technology,Xi´an 710048,China;China Railway First Survey and Design Institute Group Co.Ltd.,Xi´an 710043,China)
出处
《振动工程学报》
EI
CSCD
北大核心
2021年第4期721-729,共9页
Journal of Vibration Engineering
基金
国家自然科学基金资助项目(52039008,51779208,51479165)。
关键词
深厚覆盖层
高土石坝
夹层液化
场地卓越周期
反应谱
deep overburden site
high earth-rock dam
liquefaction of the interlayer
predominant period of site
acceleration spectrum
