Under the situation that the frequency of rainfall-induced shallow landslide and debris flow, which may be attributed to climate change is increasing, the electrical prospecting has been applying for landslide risk assessment by focusing on fine particle distribution and soil water characteristic change of subsoil extensively. In this study, both the distribution of electric resistivity and the volumetric moisture content measured at the fill slope comprising weathered granite residual soil in Chiang Mai, Thailand were presented. Consequently, the comparison of electric resistivity and volumetric moisture content measured at the slope has revealed the characteristics on the significant change of electric resistivity during rainy season and dry season, which is limited to shallow area. Furthermore, based on findings obtained through this study, the applicability of electrical prospecting for landslide risk assessment for slopes at different geotechnical condition and different weather condition has been discussed.

In the Great East Japan Earthquake, landslide deformation was found on many hillside residential lands in Sendai City. This deformation occurred in embankments having a large fraction of fine-grained content, where liquefaction was less likely to occur, and therefore differed from the deformation of an embankment resulting from liquefaction. This study analyzes physical, mechanical and underground water characteristics of moving segments of embankments where landslide deformation occurred, and considers the factors and mechanisms that caused the landslide deformation through simulation, using dynamic effective stress analysis and other methods. The results show that plastic deformation occurs even in embankments with a lower probability of liquefaction because the cyclic loading caused by large earthquakes increases the pore water pressure in saturated segments with a degree of compaction of 89% or less in an embankment and in unsaturated segments (saturation degree of 80% or more). It is also demonstrated that the excess pore water pressure ratio increased by cyclic loading is almost the same as the excess pore water pressure ratio when shearing fracture occurs; this is derived from the results of static triaxial compression tests conducted on embankments.

The aim of this paper is to report a new developed in-situ permeability testing device which is broadly applicable to tests for the ground above water table. There are various conventional methods or devices of testing in-situ permeability above groundwater table. Meanwhile, they can only apply to the vicinity of the ground’s surface and the applicable area is limited. Considering this background, our new testing device is developed to perform the packer test using an auger borehole in the shallow ground. In this paper, we explain the characteristics of our development device, and we also propose a new calculation formula of field-saturated hydraulic conductivity which can be applied to the packer test when the water table is comparatively shallow to affect the infiltration flow rate during the test. The field-saturated hydraulic conductivity was calculated by applying the proposed formula to a ground and it was also compared with the result of the other in-situ test and the simulation result. Consequently, the applicability of the formula is validated.

Kosa mainly comprises soil particles swept-up by strong winds over arid landscapes. This dust is transported by westerly winds over wide areas. Such dust emissions are known to collapse the soil crust. Typically, the relation between the grain size and critical friction velocity is considered in a numerical model for the dust, without considering the collapse of the crust. Thus, the numerical model for dust yields inaccurate results. Herein, the soil sample is collected from the collapsed crust created. The soil particles are allowed to collide with glass beads at a fixed incident angle and variable incident velocity. The simulation is observed using a high-speed camera. Results reveal that the number of released particles and the incident velocity of the glass beads could be linearly approximated and that the emitted particles reach a height of ~20 mm from the surface of the soil sample.