Tatsuya Ishikawa

This paper describes a new testing method to examine the mechanical behavior of railroad ballast subjected to repeated train passages on ballasted track. Two types of cyclic loading tests, namely a single-point loading test and a moving-wheel loading test, were performed with small-scale models of ballasted track. Next, a “multi-ring shear apparatus” was developed as a type of torsional simple shear apparatus, and the applicability of a newly proposed multi-ring shear test to an element test of

The aim of this study is to evaluate the effects of freeze–thaw action on the water retention–permeability characteristics of volcanic coarse-grained soils under unsaturated conditions in order to examine the hydraulic behavior of volcanic soil during the snow-melting season. In this study, a series of water retention, permeability, and slaking tests on three types of crushable volcanic coarse-grained soils, differing in their degrees of particle crushability, were performed under various degree

The 2018 Hokkaido Eastern Iburi earthquake with the JMA seismic intensity of 7 occurred at a central south part of Hokkaido, Japan at 3:08 a.m. on September 6, 2018. Considering the social importance of this historical earthquake-induced geo-disaster, the Japanese Geotechnical Society (JGS) organized a “JGS Survey Team for Geotechnical Disasters in Hokkaido, Japan Induced by the 2018 Hokkaido Eastern Iburi earthquake,” mainly comprised of experts from the industry and academia of the Hokkaido br

This study examines the mechanism of the geohazards occurred at a volcanic soil slope in cold regions and its influencing factors in consideration of the effects of freeze-thaw actions on the physical properties, the water retention-permeability characteristics, and the deformation-strength characteristics of volcanic soils from the viewpoint of both experimental study and analytical study. To this end, we performed the long-term field measurement, model tests, laboratory element tests, and nume

In Hokkaido, Japan, soil slope failures occur frequently during the snow melting season. These slope failures are triggered by the excess amount of water derived from snowmelt and rainfall. For the prediction of snowmelt-induced soil slope failures in seasonally cold regions, an early warning criterion is required. The existing Japanese early warning criteria for sediment disasters, i.e., the relationship between the 60-min cumulative rainfall and the Soil Water Index (SWI), the effective rainfa