松原Ms5.7级地震砂土液化场地地脉动特性

Microtremor characteristics of sand liquefaction sites during Songyuan Ms5.7 earthquake

基于松原Ms5.7级地震砂土液化场地为研究对象,探究液化场地和非液化场地的地脉动H/V谱的卓越频率和波形的相关特性,为地震应急期间快速判别砂土液化提供基础资料。本文首先介绍此次地震砂土液化震害情况,其次讨论不同水平组合方式、不同窗函数、不同步长对数据处理的结果影响,最后通过对比分析选定合理数据处理参数,并对26个场地地脉动测试数据进行分析。结果表明:发生液化场地的地脉动H/V谱比的卓越频率范围为0.8~1.8 Hz,波形呈现单一或者双个波峰,且波形趋于某一谱比值;而未发生液化场地的地脉动H/V谱比的卓越频率为1.6~1.7 Hz,波形呈现单一波峰或者呈现出无明显波峰,且波形呈现递减趋势。

Taking the sand liquefaction site of the Songyuan Ms 5.7 earthquake as a research object,the predominant frequency and waveform characteristics of the microtremor H/V spectra in liquefaction and non-liquefaction sites were explored for providing a basis for rapid identification of sand liquefaction during earthquake emergency. The seismic damage of sand liquefaction in Songyuan earthquake was introduced,and the effects of horizontal component combination,spectral window and smooth length on data processing were discussed. Comparisons were performed to determine reasonable data processing parameters and the test data of microtremors at 26 sites were analyzed. The results show that,for the liquefaction sites,the predominant frequency of microtremor H/V spectral ratio is in the range of 0.8 Hz to 1.8 Hz,and that the waveforms have single or double peaks and approach a certain spectral ratio. For the non-liquefaction sites,however,the predominant frequency of microtremor H/V spectra varies from 1.6 Hz to 1.7 Hz,and the waveforms show a single peak or no obvious peak and has a decreasing trend.