This paper presents the long-term prediction of the ground behavior, including secondary consolidation via the particle filter, using model test results. There have been some difficulties in evaluating the behavior, such as two-dimensional displacements, because an unsuitable value for Poisson’s ratio and the constitutive model are generally employed for consolidation problems. This paper identifies Poisson’s ratio in addition to the compression index, the permeability, the initial volumetric strain, and the secondary compression index, and adopts the modified Cam-clay model, considering anisotropy, to overcome the problem. The prediction is performed using the identified parameters, and numerical examples of accurate predictions of the ground behavior are shown.

Skin fricrion may be one of the most critical factors in designing the prebored and precast pile. Special attention was given to the interface behavior of pile-cement milk-surrounding soil during the installation of prebored ans precast pile. The case of single pile was analyzed through a three-dimensional finite approach. It is shown that the settlement of the pile is increased as the friction coefficient between the cement milk and soil is decreased. A parametric study on the effect of thickness of the cement milk and water-cement ratio of the cement milk filling the prebored hole, on pile settlement was also conducted. Based on this, it is found that, as the thickness of the cement milk and the water-cement ratio decreased, the settltment of the pile is decreased. It is also found that the reduction in settlement is much less favorable for a skin friction pile than for an end bearing pile.

For the widening and slope surface repair of the embankment, cover soil is placed on the existing embankment slope. To stabilize the cover soil, the slope stabilization method we have developed for existing embankments using small diameter steel pipes with blades is adopted. Since the pipes are perforated in order to provide drainage function, the pipes are installed laterally. In this study, to verify reinforcing effects of laterally installed steel pipes into the embankment, unloading experiments are carried out in the geotechnical centrifuge and on an actual embankment.

In recent years, the construction of precast arch culverts, which include hinges in the main body, has been increasing. Precast arch culverts have hinge function, and thus, the evaluations of the mechanical behavior in construction process and the dynamic interaction between the soil and the culvert has become an important issue. The authors conducted 1/5 scale shaking table test to clarify the seismic behavior of a three-hinge precast arch culvert. Furthermore, the inner space displacement and the earth pressure of the culvert were measured at each construction stage. In this study, the relationship between the deformation of the culvert and the earth pressure acting on the culvert during construction process is discussed. From the results, it has been confirmed that the horizontal earth pressure acting on the culvert is larger than the earth pressure at rest because of the passive earth pressure when the banking height is higher than the crown.

Tunnel excavations in urban areas are highly restricted by the need to control the blasting vibration level and obtain rapid excavation. A new tunnel excavation method using an abrasive waterjet (AWJ) system assisted by mechanical excavation tools is now under development for efficiently creating tunnels and underground spaces, such as generating a continuous free surface on the tunnel’s perimeter. This artificial continuous free surface can increase the efficiency of the excavation rate and even enhance the excavation rate at various free surface conditions. In this study, an in-situ experimental test was performed to verify the free surface effects on excavation performance. A continuous free surface is generated using an abrasive waterjet system. Mechanical excavation tools (drilling jumbo or hydraulic rock breaker) are utilized to excavate the remaining tunnel face. According to the in-situ experimental results, we expect that this new tunnel excavation method can be effectively utilized as baseline data for establishing new alternative tunneling methods in various construction locations, such as short tunnels near urban areas, utility tunnels, and shafts

This paper discusses an experimental study on the effects of soil plugging on the inner frictional resistance of bottom thick-walled open-ended piles. The piles were penetrated in both dense and loose sand, prepared by 60 and 30% of relatively densities respectively. Open-ended piles of 30 and 50mm outer diameters were used in the study. A sleeved and non-sleeved open-ended pile each were used in addition to the respective closed-ended piles. The sleeve height of the sleeved open-ended piles was designed as a 2D length (D is pile outer diameter). The degree of soil plugging is discussed using the incremental filling ratio. The results suggest that the loose ground is more effective to use the bottom thick-walled open-ended piles regardless of the pile diameter. The results also indicate that the larger diameter piles are more effective to use the bottom thick-walled open-ended piles. The results of soil plugging indicate that the influence of ground density is not significant in relatively smaller diameter piles than relatively larger diameter piles.