Seismic Response of Earthfill Dams: Shear Beam Analysis vs Field Observations

Abstract

Earthfill dams are critical infrastructure and perform as a system by integrating various components such as foundation, core, shell, filter, outlet and spillway. To analyze the entire response, it is important to properly identify the dynamic characteristics of the system based on observations. This paper investigates analytical solutions of the shear beam approach to identify the dynamic characteristics of existing dams considering variable shear modulus with height. To this end, the governing differential equation is first solved in terms of Bessel functions. The corresponding response parameters are then derived for different modes. Results are presented for a range of expected shear wave propagation velocity profiles with depth. Transfer functions are derived from the bedrock to the crest for different shear modulus variations and levels of material damping. Fundamental periods are obtained from the analytical solutions and compared to the empirical observations from 2 dams in Japan to estimate the shear wave velocity profiles of the dams.