Study on Liquefaction Characteristics of Volcanic Ash Soil

Abstract

In the conventional design method, there is no particular method to judge the liquefaction phenomenon of the unusual soil such as volcanic ash soil. This study, in order to clarify and evaluate the liquefaction characteristics of volcanic ash soil, field investigations and a series of soil laboratory tests of volcanic ash ground were carried out. The field investigations and sampling were conducted in the areas where ground liquefaction occurred due to the 1993 Hokkaido-nansei-oki and the 2013 Tokachi-oki earthquakes. According to the results, the liquefaction strength ratio (RL) was underestimated when using the formulation of the conventional design method. Moreover, it was found that the estimated formulation RL need to be modified for evaluating the liquefaction phenomenon in volcanic ash soil.

Evaluation of failure of slopes with shaking-induced cracks in response to rainfall

“…Earthquakes and rainfall are two common natural disasters causing landslides (Keefer 1984;Schuster et al 1996;Crosta 2004;Sassa et al 2015) in various mountainous areas worldwide. Earthquake-induced landslides mainly resulted from liquefaction of saturated deposits (Cornforth 2005;Sassa et al 1996;Okada et al 2000;Uzuoka et al 2005;Wang et al 2014;Egawa et al 2018;Kameda et al 2019), sliding of the main body on a plane of weakness (Chigira and Yagi 2006;Chigira 2012), or marginally stable slopes (Seed and Goodman 1964;Seed 1966;Ling and Chigira 2020). Studies on the seismic response of slopes or embankments to earthquakes were also carried out by different researchers using various methods including centrifuges model tests (Matsuo et al 2002;Liang and Knappett 2017), numerical simulations (Uzuoka et al 2005;Xiong et al 2014), and shaking table tests (Koga and Matsuo 1990;Matsumaru et al 2012).…”