Modulus reductions of dam embankment materials based on downhole array time series

Abstract

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.

Application of the Lagrange Equation for Intelligent Sensor Vibration Control for Power Network Monitoring

“…Earthquake disasters have two characteristics: suddenness and destructiveness. Previous earthquake disasters have caused incalculable loss of life and property in my country [2]. Research on the vibration control of building structural systems, combining the unique two-level structure of giant structures with structural vibration control technology, and the emergence of a new type of giant vibration reduction system, can not only reduce the impact of earthquake damage but also solve the problem of difficult earthquake resistance of high-rise structures to a certain extent, which is of great significance for engineering earthquake resistance [3].…”