Response analysis during liquefaction considering unsaturated soils

¹ Obayashi Corporation, Nuclear Facilities Division, 2-15-2, Konan, Minato-ku, Tokyo, Japan
² Obayashi Corporation, Technology Research Institute, 2-15-2, Konan, Minato-ku, Tokyo, Japan
³ Central Research Institute of Electric Power Industry, Sustainable System Research Laboratory, 1646 Abiko, Abiko-shi, Chiba, Japan
⁴ Tohoku Electric Power Company, Inc., Civil and Architectural Engineering Department, 1-7-1 Honcho Aoba-ku, Miyagi, Japan

^* Corresponding author: nagai.hideki@obayashi.co.jp

Abstract

This study aims to clarify the soil-structure interaction during earthquakes for an underground vertical shaft, which serve as an important facility of a nuclear power plant, constructed in a dense sand layer with a low groundwater level. To achieve this objective, numerical analyses were conducted to reproduce a series of centrifugal loading tests that included an unsaturated soil layer. Additionally, it was attempted to clarify the dynamic interaction between the soil and the structure, particularly focusing on the difference in lateral earth pressure exerted by the surrounding soil above and below the groundwater level. By conducting detailed investigations using three-dimensional effective stress analysis, the study confirmed the usefulness of this method for structural design in seismic conditions.