In this study, behaviors of the volumetric water content and the soil suction due to rainfall infiltration and drainage characteristics under relatively high suction state were discussed through the macro-pores part and the matrix part separately based on the results of in-situ measurement made at the fill slope where macro-pores developed. As a result, despite the volume water content drops below the field capacity at the start of in-situ rainfall and the pore pressure is less than the corresponding values, the process of rainfall infiltration and drainage characteristics exhibited along the boundary drainage of the matrix flow at maximum field capacity corresponds to the scanning curve. In addition, even if the installation position of the measurement interval was about 0.4m in this slope, the extremely heterogeneous distributions in volumetric water content and pore pressure lead to a lack of synchronicity observed between the volumetric water content and the pore pressure when the macro-pore flow occurred. Therefore, the effect of the measurement interval should be considered when interpreting the measurement results.

 In this study, based on the in-situ measurement results on the fill slope where macro-pores were developed, the influence of preferential flow due to heterogeneous pore distribution on rainfall infiltration and drainage characteristics was discussed. As a result, the following possibilities are shown.

 First, in the slope where macro-pores have been developed, when pore-water pressure and volumetric water content increase rapidly due to rainfall, a preferential flow occurs as the permeability of soil containing macro-pores increases by several orders. And since the preferential flow forms a pseudo-saturated region in a short time, the pore-water pressure increased almost coincident with the rainfall peak due to the subsequent high-intensity rainfall. Accordingly, it is considered that since this pore-water pressure transmission occurs in a short time, the occurrence time of the shallow slope failure may be much faster than the result estimated by the conventional seepage flow analysis same as the past slope failure incidents.

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.

Slope failures occasionally happened due to unstable masses during excavation of the toe of undercut slopes or weakening basal support after backfilling process can cause delay in open-pit mining. As one of countermeasures against slope failure in mining stage, a temporary slope reinforcement with stabilizing piles which is delaying a slope failure are undertaken at Mae Moh lignite mine in Thailand. In order to improve the efficiency and safety in mining, alignment of stabilized piles for mitigating undercut slope failure remains a challenging to study. In this study, reinforcement effects and failure mechanisms were investigated using a series of physical model of undercut slope with different alignments of shear pins by image analysis. It was found that the basic characteristics of shear pins have effects on a critical width of undercut slope and triggering mechanisms of slope instability.

 In mountain tunnel construction projects, discrepancies between the rock classifications specified at the basic design stage and the rock classifications applied at the actual construction stage often cause significant cost overruns. Therefore, it is expected to improve the accuracy of the rock classification estimated based on the preliminary geological survey. From this point of view, the authors proposed a methodology related to rock classification estimation by artificial neural network. However, past studies have been conducted under the condition that available tunnel data sets are limited. In this study, we focused on the influence of the increase in training data on the estimation results and examined the applicability of the proposed method. As a result, in addition to the increase of the indexes applied to the data set, it was found that deep learning of various rock states is effective to improve the accuracy of rock classification estimation.

This study expects to demonstrate that a) basal deformation and roughness have influence on stress distribution within embankments and b) implementing of Bézier Extraction in IsoGeometric Analysis (IGA) substantially improves the numerical robustness. Two-dimensional elastic solutions of embankment to which the prescribed basal deformation of either subsidence or uplift and different condition of either fully rough or fully smooth base has given were compared and discussed, focusing on the variation of pressure profiles. The numerical results obtained from IGA were validated with those of finite element method (FEM), revealing that the performance of IGA under Bézier extraction is superior to FEM by achieving the lower computational resources necessary to obtain the same accuracy.

In order to increase the maximum width to which the slope can be undercut, slope stabilization shear pins is required. In this study, two layout patterns of pencil leads, 2 mm in diameter, were placed into physical models of undercut slope made of a confined block of humid silica sand No.6 resting a Teflon plate. The soil pressure and slope movement during which the slope was undercut from the center line until reaching the failure were monitored by a set of pressure gauges, digital camera and high-speed VDO camera. The experimental results revealed that for a given similar number of pencil leads, the layout in vertical row has a higher influence on the stability than that in horizontal row.