玉野 富雄

本研究では，近世城郭石垣や石橋に代表される石造構造物の力学安定性を評価するための工学指標として，外力一定条件下での単位石温度変化に対するひずみ変化の関係である「温度−ひずみ係数」について示した。計測事例として，2か所の近世城郭石垣および1か所のアーチ型式石橋を取り上げた。2か所の近世城郭石垣においては，石垣の変形状態を数値化した「石垣はらみ出し指数」と「温度−ひずみ係数」の関連性について考察した。あわせて，これらの計測事例が，今後の近世城郭石垣の力学安定を評価する際の参考とできることを示した。

The Japanese castle masonry wall (hereafter simply "wall"), constructed from the late 16th century to middle of the 17th century, is appreciated as one of the world's finest and most outstanding example of construction. The walls are meted for their mechanical rational structure, especially the two-dimensional curved surfaces (hereafter referred to as hiranosuki) found on the three-dimensional structures. Regarding hiranosuki, further study is needed to clarify the technique of attaching them to the wall during reconstruction. In accordance with this viewpoint, this paper presents field measurements of the hiranosuki of Tokugawa-Osaka Castle walls. Next, the mechanical effects of hiranosuki is discussed, based on the analytical results of the field measurement data and three-dimensional FEM analyses.

This paper presents the generation mechanisms of pull-out resistance of pressurized friction-type anchor at the cases of single anchor and group anchors. At the case of single anchor, it is shown that the ultimate pull-out resistance of pressurized friction-type anchor increases to 1.3～1.6 times compared with the resistance of non-pressurized friction-type anchor and the effect of mechanics of pressurizing is remarkable. At the case of group anchors, it is clarified that the slipping masses from both sides between anchors intersects and combines when anchor installation depth (D) and ratio (D/B) at anchor intervals (B) grows more than 1.43 by the strain analysis using PIV and it leads to the large decrease in the ultimate pull-out resistance.

This paper describes the engineering performances of Suiken Dike certified as a heritage site by Wakayama Prefecture. The dike was constructed by using excellent construction techniques in Edo period. Especially, the main part of the dike is covered with many rectangular solid stones like a stone wall of a Japanese castle. The soil part is attached with the stone part. However, a functional role of this composite structure is unknown. We carried out the FEM analyses to study interactive effects between these two parts against wave forces as a coastal dike. A Tsunami wave force and a violent wave force due to a typhoon were used as an external force. It was clarified that the soil part effectively functioned to restrain the stone part rotating to the back side.

In this study, impact splitting tests were carried out by loading cylindrical granite specimens horizontally and obtaining the crack propagation velocities by an image analysis using a super-high-speed video camera, which has the fastest frame rate in the world. The relationship between the impulse and the crack propagation velocity indicates that there appears to be a critical state at which the crack propagation velocity does not exceed a certain value even if an increased impulse is applied. The critical value obtained for the granite specimens was 2.6 km/sec. © 2009 IOS Press.

In this study, impact splitting tests were carried out by loading cylindrical granite specimens horizontally and obtaining the crack propagation velocities by an image analysis using a super-high-speed video camera, which has the fastest frame rate in the world. The relationship between the impulse and the crack propagation velocity indicates that there appears to be a critical state at which the crack propagation velocity does not exceed a certain value even if an increased impulse is applied. The critical value obtained for the granite specimens was 2.6 km/sec. © 2009 IOS Press.

In this study, the static and impact splitting tensile tests were carried out by loading the cylindrical mortar/granite specimens horizontally, and the crack propagation velocities were obtained by the image analysis using the ultra high-speed video camera, which is the fastest in the world, developed by Etoh et al.(2003). The correlations between the impulse and the crack propagation velocity indicate that there appears to be a critical state in which the crack propagation velocity does not exceed a certain value even though the increased impulse is applied. The critical value obtained was 2.6km/s for both mortar and granite specimens. Furthermore, crack propagation velocity determined by the image analysis was verified by the dynamic strain analysis.

The purpose of this research is to explore the mechanism required for the generation of earthquake vibration on the propagation velocity of the crack in fault plane. In this research, the impact splitting tensile tests of mortar and granite were carried out, and the propagation velocity of the crack was visualized and obtained by image analysis using ultra high-speed video camera. A relationship between the impulse which is impact loading and propagation velocity of the crack was observed. There appears to be a critical state in which propagation velocity does not increase, even if impulse is increased over it. It was proven to converge in 2.6 km/sec. Next, the mechanism of the development of the dynamics of the crack by the impulse was examined from displacement vector and Particle Image Velocimetry (PIV) analysis.