Journal of Natural Disaster Science

SEISMIC RESPONSE ANALYSES OF GROUND WITH IRREGULAR PROFILES BY THE BOUNDARY ELEMENT METHOD

Kenzo TOKI
Professor
and
Tadanobu SATO
Associate Professor, Disaster Prevention Research Institute, Kyoto University, Kyoto

(Received 2 Feb., 1983 and in revised form 15 Aug., 1983)

Abstract

The effect of the soil profile on seismic ground motion was investigated for incident SH waves. Several types of filled valleys were analyzed. The boundary element technique was used in the numerical integration of the field equation. In a wedge type model, the dip angle has a great effect on the seismic response of surficial ground. The response of ground at high frequency ranges varies greatly along the horizontal. There is a very large response at ground surface in the transient region from deep to shallow ground for a particular incident angle. In the model of the multi-layered ground included in an geologically irregular region, a surface wave is generated if the multi-layered zone is greater than a certain size. In the prototype model of an actual basin that extends several tens of kilometers, the frequency characteristics of the input earthquake motion affect the response magnitude of surficial ground. Ground motion also is affected by local irregularities in the ground just below the observation site and by distant irregularities.

Key words

seismic response, irregular ground, boundary element method