Evaluation of short-term stability for sea-wall structure at Kobe Airport

Abstract

Prior to the huge reclamation work for constructing Kobe Airport, the sea-wall structure resting on a 30m-thick soft Holocene clay layer in the 16m-deep sea was constructed at stages over the period of three years. Regarding the design of short-term stability of the sea-wall structure, the ratio of undrained shear strength of the normally-consolidated seabed clay to in-situ yield stress was estimated to take the value of 0.35 in order to satisfy the factor of safety in excess of 1.3. This design strength in the clay foundation was checked with the unconfined compression strength of the fresh clay samples retrieved from boreholes during the construction. In this paper, the short-term stability of the embankment in this well-documented case history was re-evaluated after-the-event with the results of comprehensive series of constant-volume direct shear box tests in which the effects of strength anisotropy as well as the shearing rate on undrained shear strength were both examined. Discussion is made how to estimate the short-term stability of the embankment by considering the effects of strength anisotropy and shearing speed on undrained shear strength and how it is linked with the current design method in Japan in which a half of the undrained compression from unconfined compression test is employed.

Geotechnical characteristics and seismic stability evaluation of pumice-fall deposits soil on collapse slope by the 2018 Hokkaido eastern Iburi earthquake

“…In this study, we focus on the shear strength of the soil elements induced by seismic motion. It is known that the shear strength of soil elements with elasto-viscoplastic properties depends on the shear rate (Ovando-Shelley 1995;Duttine et al 2008;Shibuya et al, 2008;Kokusho 2019). Kameda (2022) have reported rheological properties for the Ta-d soil type investigated in this study.…”

Stability for a high embankment founded on sulfide clay

“…50 have been suggested for different types of soils in numerous studies (e.g. Chung et al, 2007;Jardine and Hight, 1987;Karlsson and Viberg, 1967;Kim et al, 2009;Ladd, 1991;Larsson, 1980;Mayne, 1980;Mayne and Mitchell, 1988;Nicholson and Jardine, 1981;Shibuya et al, 2008;Suzuki and Yasuhara, 2007;Tanaka, 1994;Watabe et al, 2002). From these studies it can be concluded that the s u =ó 9 p ratio varies with soil type.…”

“…Several recently published studies have adopted total stress analyses to evaluate stability during staged construction (e.g. Shibuya et al, 2008;Watabe et al, 2002). A total stress analysis based on the initial undrained shear strength s u0 in the clay would in most cases be conservative (i.e.…”