The present author previously proposed energy-based evaluation on earthquake-induced slope failures of long travel distance essentially for natural slopes.　As a next step, simplified numerical analyses are conducted for relatively small slope displacements where the Newmark type straight slope model, with various slope angle, stiffness and sliding soil thickness, is shaken by one-dimensionally propagating harmonic SH wave, and the earthquake energy dissipated in slope sliding as energy difference between upward and downward waves is confirmed identical to the friction energy by the sliding.　A series of numerical analyses have clarified that residual slope displacements δr are uniquely correlated with the dissipated wave energy determined from upward wave energy using various pertinent parameters.　The upward wave energy at a slope can be calculated from incident energy at a base layer using empirical attenuation formula.　This indicates that δr can be readily evaluated without using acceleration time-histories unlike the conventional Newmark method.　The evaluation procedure has been developed based on the numerical results and previous studies on how wave energies during earthquakes are determined.　An example study for road embankment displacements of varying hypocenter distances during a M6.8 earthquake conducted using the method has indicated consistency with a corresponding case history.

In a geotechnical investigation for detached houses, preliminary surveys and the Sweden weight sounding test are commonly used. When a consolidation subsidence is considered, it is generally preferable to perform a consolidation test using samples by a method for obtaining soil samples using stationary piston sampler. However, it is rare to carry out for economic reasons. Therefore we aimed for it becoming general in conducting the design work by obtaining the necessary soil test result from the good quality soil samples by the proposed simple sampling method. In this paper, we compared the soil test results using samples by three types of sampling method at several sites, and examined the usefulness from the quality evaluation. As a result, we revealed an economical and simple sampling method which can extract good quality samples with less disturbance than the fixed type.

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.

Capillary barriers (CB) composed of a fine soil layer overlaid on a coarse soil layer exhibit excellent characteristics. Water which infiltrates into the soil is suspended just above an interface between the soil layers and diverted along the interface, with the result that a downward movement of water into the deeper soil layers below the interface is restricted for some length along the interface. Because of this diversion of infiltration water, the CB system has been employed in a top cover on waste landfills to reduce water infiltration into the protected waste materials. Also, the CB system is being considered as a top covering of shallow soil for extremely low-level radioactive waste repository and intermediate storage facility. However, there are still few examples of CB construction. Suitable materials for the fine soil layer and coarse soil layer used to make a CB are not confirmed. In particular, it is important to clarify that the fine soil has sufficient influence on the diversion length of the CB system. In this paper, the theoretical equation proposed by Ross-Steenhuis et al., fine soil permeability, water retention, are used to clarify an appropriate sand for maximizing diversion length. Moreover, a large soil layer experiment used fine soil with material properties that can maximize the diversion length of the CB system and clarified the material properties of a fine soil to maximize the diversion length of the CB. In addition, the authors clarified the applicability of the theoretical equation proposed by Ross-Steenhuis et al.

In this research, we conducted a series of pull-out test of geogrid in soil focusing on the characteristics of pull-out box, such as its size or type, and clarified the influences of those factors on the test results. Moreover, we examined the problems of pull-out test including the necking of geogrid specimen and the arch action caused by front wall. As a result, it turned out that the size of pull-out box, the shape of pull-out sleeve and the stiffness of front wall have a great influence on the results of pull-out test while the shape of the box’s rear-end part as well as the loading method of pull-out load have a little influence on the frictional strength parameter obtained from the test. Furthermore, it was also found that the pull-out resistance mechanism differs depending on the form of geogrid, and that the pull-out resistance of geogrid with rough surface and small aperture is overestimated because of the influence of arch action.

In general, the pulling-out method is adopted for removing existing piles, in particular the method to pulling-out the head of a pile with a wire rope is used. However, there is a possibility of leaving a part of the existing pile in the ground in the case of a damaged existing pile, and it is possible to induce inhomogeneous pulling-out hole with backfilling due to injecting fillers from the top of the purring-out hole. Because the method of powerfully chucking the tip of existing pile (PG method) embraces and lifts the entire existing pile, it is possible to reliably withdraw even existing damaged piles. Also, because the fillers are injected from the lower part of the pulling-out hole, homogenous backfilling is possible over the entire depth of the pulling-out hole. This paper describes the characteristics, safety and improvement of construction quality by the PG method as one of the existing pile pulling-out methods, based on findings clear from the its construction theories and construction examples.