Surface-to-base amplification evaluated from KiK-net vertical array strong motion records
Surface-to-base amplification evaluated from KiK-net vertical array strong motion records
复制标题
根据 KiK-net 垂直阵列强运动记录评估地基放大
DOI：
10.1016/j.soildyn.2007.10.016
复制
发表时间：
2008
影响因子：
4
通讯作者：
Katsuharu Sato
中科院分区：
文献类型：
--
作者：
T. Kokusho;Katsuharu Sato
场地放大定义为频谱比的峰值进行了研究，在日本的三次大地震期间，使用在一些KiK网井下阵列记录的表面和基底加速度。一个重要的任务是确定光谱放大相对于露头运动的帮助下，井下阵列记录。基于可用于单个阵列的土壤数据，计算并调整理论扩增以与阵列记录的峰值扩增一致。对于不同地点和不同地震，在由此获得的峰值放大率和S波速度比之间发现了良好和独特的相关性，S波速度比由基底层中的S波速度除以平均S波速度Vs ′定义。根据基模频率和施加峰值放大的等效表面层的厚度来评估Vs '的值。常规参数[公式：见正文] ;现行设计规范中使用的顶部30 m处的平均剪切波速度，与获得的放大率没有很好的相关性。建议不仅可以从Vs测井数据而且可以从微动测量确定Vs '。
Site amplification defined as the peak value of spectrum ratio was investigated using surface and base accelerations recorded in a number of KiK-net down-hole arrays in Japan during three major earthquakes. An important task was to determine the spectral amplifications relative to outcropping motions with the aid of the down-hole array records. Based on soil data available for individual arrays, theoretical amplifications were calculated and adjusted to coincide with the peak amplifications of the array records. A good and unique correlation was found between the peak amplifications thus obtained and S-wave velocity ratios, defined by S-wave velocity in base layer divided by average S-wave velocity Vs¯, for different sites and different earthquakes. The value of Vs¯ was evaluated from fundamental mode frequency and the thickness of an equivalent surface layer in which peak amplification is exerted. The conventional parameter [Formula: see text] ; averaged shear wave velocity in the top 30m used in current design codes, did not correlate well with the obtained amplifications. It is suggested that Vs¯ may be determined not only from Vs-logging data but also from microtremor measurements.