摘要
以云南省昆明地区为例,对28个钻孔分别以20 m、25 m、30 m厚度计算等效剪切波速和卓越频率,同时测定场地脉动优势频率.结果显示:以20 m、25 m、30 m厚度计算的等效剪切波速,其后者一般都大于前者.对多数钻孔,用25 m厚等效剪切波速和卓越频率判定的场地土类别一致;少数钻孔在靠近30 m时二者判定结果一致.经测定,场地脉动优势频率与20 m厚波速卓越频率相近,但却明显高于25 m厚波速卓越频率.脉动优势频率与不同计算厚度的等效剪切波速度相关性基本相同,对同一厚度(深度)脉动优势频率随等效剪切波速度增加而增加.若等效剪切波速度相等,则深度小的脉动优势频率高.由此推出,脉动优势频率主要由地表层20 m厚岩土力学性质决定,而且越靠近表层的岩土力学性质对脉动优势频率的影响越大.本文从弹性力学理论证明了脉动优势频率和剪切波速度的关系式.通过进一步分析证明,用25 m厚等效剪切波速判定场地土类别更可靠,用脉动优势频率判定场地土类别可作为有效的辅助方法.它们将影响对场地类别的判定.
Take Kunming area for example,we compute equivalent shear wave velocities and dominant frequencies of S-wave velocities for 28 drill holes with thicknesses of 20 meters,25 meters,and 30 meters severally,meanwhile,determine predominant frequencies of site microtremor.The results of calculation shows that the equivalent shear wave velocity increased with thickness(depth).For most drill holes,the classifications of site soil severally judged from equivalent shear wave velocities and dominant frequency of wave velocity computed with thickness of 25 meters are accordant.For a few,the classifications of site soil severally judged from equivalent shear wave velocities and dominant frequency of wave velocity computed with thickness of nearly 30 meters are accordant.The predominant frequency of site microtremor is close to the dominant frequency of 20 meters’velocity,and apparently higher than the dominant frequency of 25 meters’wave velocity.The calculated relativities between predominant frequency of microtremor and equivalent shear wave velocities with different thicknesses are equal nearly.For the same depth predominant frequency of microtremor increases with equivalent shear wave velocities increasing.For the same equivalent shear wave velocity,the lower the depth,the higher the predominant frequency of microtremor.From here we see that the predominant frequency of microtremor is determined by 20 meters’geotechnical mechanical properties of the surface layer.And the closer the surface layer,the greater influence the geotechnical mechanical properties.The relation between predominant frequency of microtremor and equivalent shear wave velocity is proved by the theory of elasticity.Further,the analysis suggests that 25 meters’equivalent shear wave velocity is more suitable for classification of site soil,and predominant frequency of microtremor can be used as an effective auxiliary method for the classification of site soil.The predominant frequency of microtremor and the equivalent shear wave velocity have an impact on the classification of site soil.
作者
赵淑芳
石宝文
许峻
崔建文
许昭永
ZHAO Shu-fang;SHI Bao-wen;XU Jun;CUI Jian-wen;XU Zhao-yong(Kunming Southern Geophysical Technology Company Limited,Kunming 650231,China;Kunming Junqi Undestructive Testing Technology Company Limited,Kunming 650051,China;Anti-Disasters Institute of Yunnan Province,Kunming 650224,China)
出处
《地球物理学进展》
CSCD
北大核心
2019年第6期2533-2541,共9页
Progress in Geophysics
关键词
等效剪切波速
脉动优势频率
波速卓越频率
场地土类别判定
差异分析
Equivalent shear wave velocity
Predominant frequency of microtremor
Dominant frequency of wave velocity
Classification of site soil
Analysis of variance
作者简介
第一作者:赵淑芳,女,1983年生,山西运城人,工程师,主要从事地震工程相关工作.(E-mail:153117060@qq.com);通讯作者:石宝文,男,1986年生,云南丽江人,工程师,主要从事地球物理勘探工作.(E-mail:shibaowen7@163.com)。
