Tetsuo Fujiyama

The Evaluation of Ground Properties and its Application to the Automatic Control of Vibratory Soil Compactors

A ground-evaluating method was suggested which makes use of the behaviour of an exciter that vibrates on the ground. Numerical simulations were carried out to investigate the relationship among the vibrating behaviour of the exciter, the ground stiffness and the vibrating conditions of the exciter, -A method that evalu ates the :groundstiffness with the vibrating behaviour of any. exciter was derived from the rests of the numerical simulations. The applicability of this method was examined by field experiments and its application to the automatic control of a vibratory soil compactor was discussed.

Elasto-Plastic FEM Analysis and Safety Evaluation of Large Rockfill Dams During Reservoir Filling

This chapter suggests a method to evaluate the safety of large rockfill dams during first filling. The stress–deformation behavior of large rockfill dams during construction and first filling were simulated using soil–water coupled elasto-plastic analysis. The validity was confirmed by comparing with actual measurements during first filling and laboratory hydraulic fracturing tests using embankment material. A tentative plan for the pre-estimation of the embankment’s hydraulic stability and first filling safety control was suggested and put into practice at an actual dam.

Spatial Discretization of a Water Head in Soil–Water Coupled Finite Element Method Analysis Using the Hybrid-Type Penalty Method

In the present soil–water coupled finite element method (FEM) analysis, a program known as deformation analysis considering stress anisotropy and reorientation (DACSAR; Iizuka and Ohta, Soil Found 27(3): 71–87, 1987), the spatial discretization procedure for representing the water head at the center of each finite element was adopted. However, it is known that the outflow of pore water from the element boundary happens to be incorrectly calculated depending on the mesh arrangement and the inclination of the boundary. To address this problem, this chapter proposes a more rigorous spatial discretization procedure for pore water flow. Namely, the hybrid-type penalty method (HPM) is introduced to spatially discretize the pore water flow in soil–water coupled finite element formulation, and the DACSAR program is modified using the proposed technique.

A FUNDAMENTAL STUDY ON THE GROUND IMPROVEMENT OF WASTE LANDFILLS BY IN-SITU HEATING TEST

近年の廃棄物処分量の増大に伴って, 満杯となり埋立てが完了する処分場が増加しているが, 処分場廃止後の有効利用に際しては, 地盤強度の不足と廃棄物に含まれる重金属の溶出の問題が課題とされている. 本研究では, 既存処分場に対して地中を加熱することにより, 焼却灰の自硬作用の促進を図り, 地盤の強度増加, 重金属を不溶化する地盤改良工法について提案している. そこで, 各種条件下で加熱養生した焼却灰供試体の一軸圧縮試験および溶出試験を行い有効性を検討した. その結果, 加熱養生条件により強度増加ならびに重金属の不溶化効果は異なり, 最適な養生条件下では極めて大きな効果があることを確認し, 本工法の有効性を示した.