Seismic analysis of a half-space containing a water-filled valley under 2D oblique incident waves by finite-infinite element method

Abstract

This paper presents for the first time the seismic analysis of a half-space containing a water-filled valley under 2D oblique P- and SV-waves by the finite-infinite element (FE-IFE) method. The equivalent seismic forces for the Chi-Chi Earthquake on the near-field boundary are calculated based on the exact free-field response. The effect of water-filled valleys on the seismic response of the half-space is a problem not well treated previously, which is considered through the soil-liquid interface in this paper. The present analysis procedure including the soil-liquid coupling is verified against Luco et al. for a half-space with an empty semi-circular canyon. New findings of this paper include: (1) The horizontal acceleration is amplified on the “near” side (to incident waves) of the valley, which is higher for filled valleys under P-waves, but decayed by the filled valley under SV-waves. (2) The effect of overlying water body on vertical acceleration is less significant for SV- than for P-waves. (3) For SV-waves with overly critical angles, the horizontal acceleration is larger for the “far” than “near” side, and larger difference exists for deeper filled valleys, coupled by amplified vertical acceleration. Additional observations were made for the numerical analysis inside the text.