A database of three-component acceleration time series recorded at downhole arrays in earthen dam cores was published by the Japan Commission on Large Dams. This study reviews the acceleration time series in nine earthfill and rockfill dams in Japan. The apparent shear wave velocities between downhole sensors in each dam during strong shakes are determined by calculating the wave travel time between the recorded time series. Transient shear strains are calculated from the differences in the displacement time series between sensors through the double integration of filtered acceleration time series. The modulus reduction curves of the in situ core materials are constructed by combining the apparent shear wave velocities and shear strains. The modulus reduction data are then compared with empirical models. Observations show considerable uncertainties and dam-dependent characteristics in the extracted in situ shear modulus. Accordingly, this study proposes a methodology to update the empirical modulus reduction model for dam core materials on the basis of observed data on downhole time series.

中文翻译：

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基于井下阵列时间序列的坝堤材料减模

日本大坝委员会公布了在土坝岩心井下阵列记录的三分量加速度时间序列数据库。本研究回顾了日本九座土石坝的加速度时间序列。通过计算记录的时间序列之间的波行进时间来确定强烈震动期间每个大坝井下传感器之间的视横波速度。通过滤波加速度时间序列的双重积分，根据传感器之间位移时间序列的差异计算瞬态剪切应变。原位岩心材料的模量降低曲线是通过结合表观剪切波速度和剪切应变来构建的。然后将模量减少数据与经验模型进行比较。观察结果表明，提取的原位剪切模量具有相当大的不确定性和与大坝相关的特征。因此，本研究提出了一种基于井下时间序列观测数据更新坝芯材料经验模量降低模型的方法。