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Volume 38 (1997 - 199･･･
- Issue 6 Pages 337-
- Issue 5 Pages 244-
- Issue 4 Pages 196-
- Issue 3 Pages 104-
- Issue 2 Pages 54-
- Issue 1 Pages 2-
Volume 38, Issue 4
Displaying 1-4 of 4 articles from this issue
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Youqing CHEN, Takashi NISHIYAMA, Haruyuki KITA, Toshinori SATO1997 Volume 38 Issue 4 Pages 196-204
Published: October 10, 1997
Released on J-STAGE: June 04, 2010
JOURNAL FREE ACCESSMicrocrack distribution patterns on the microscopic scale and splitting planes in Inada granite and Kurihashi granodiorite were examined using a fluorescent technique and image analysis. Using the fluorescent technique, microcracks which could not be detected under natural light were visualized under ultraviolet light. Characteristics of the microcracks such as orientation and total length per unit area were measured by image analysis. Microcracks observed in the specimens were divided into three groups, intracrystalline cracks, intercrystalline cracks and grain boundary cracks. Inada granite was characterized by three weak planes intersecting perpendicularly with each other, the rift plane, grain plane and hardway plane in the order of brittleness, while Kurihashi granodiorite showed no distinctive weak plane.
In the Inada granite, the rift plane was dominated by the predominant orientation of intercrystalline cracks the total length of which was shorter than that of intracrystalline cracks and grain boundary cracks, and the grain plane was coincident with the orientation of intracrystalline cracks. The grain boundary cracks showed no leading orientation. The numbers of intercrystalline cracks due to the rift plane in Kurihashi granodiorite were much smaller than that in Inada granite. However, Kurihashi granodiorite is estimated to contain the second rank of hidden splitting plane, because a predominent orientation of intracrystalline cracks and grain boundary cracks was found.View full abstractDownload PDF (7352K) -
Kaijun JIANG, Koichiro WATANABE, Tetsuro ESAKI1997 Volume 38 Issue 4 Pages 205-212
Published: October 10, 1997
Released on J-STAGE: June 04, 2010
JOURNAL FREE ACCESSThe conservation of lithic cultural heritages has recently drawn more attention worldwide. This paper presents a case study on a 150-year-old historically famous stone bridge called Takeno bridge in Kagoshima City, southwestern Japan. Weathering processes in the vicinity of the contact surface of the arch stone, consisting of welded tuff, were assessed by mineralogical and geochemical methods. It shows that during the 150 years, the chemical weathering advanced in the forms of hydration and oxidation even though the major mineral phases and the relative amounts generally have not been changed, and the leaching of the major elements out of the weathered rock has not occurred. The titanomagnetite has been oxidized to maghemite to some extent, especially at the contact surface the oxidation degree is relatively high. The weathering degree near the contact surface is about 15% and the affected depth is about 10 cm from the contact surface. By comparing with engineering properties, it turns out that the ignition loss test and magnetic susceptibility test are effective methods to evaluate the initial weathering of building stones. The hydration and oxidation would be the chemical reasons for deterioration near the contact surface of the arch stone.View full abstractDownload PDF (3784K) -
Ichiro SEKINE, Hitoshi NISHIMAKI, Kazuaki ISHIGAKI, Toshiaki HARA, Aki ...1997 Volume 38 Issue 4 Pages 213-223
Published: October 10, 1997
Released on J-STAGE: June 04, 2010
JOURNAL FREE ACCESSGeophysical investigation, by methods such as electrical and electromagnetic surveys, has recently been applied to construction projects such as underground excavation. In order to interpret resistivity profiles derived from these methods, it is necessary to study the influence of fracture and its filling materials on rock resistivity. In this paper, the influence of a fracture on resistivity of rock specimens such as granite, shale, welded tuff and tuff was investigated, and the effect of fracture filled with clay was studied. Experiments showed that the rock resistivity containing a fracture in the direction parallel to the electric current was described by the resistivity model in which intact rock resistivity and fracture resistivity are regarded as being in parallel, and the influence of the fracture filled with clay was important. The experimental results of the rock containing the fracture in the direction perpendicular to the current was described by the model in which intact rock resistivity and fracture resistivity are regarded as being in a series, and in this case the influence of fracture is little.
Based on the results of these experiments, we considered the resistivity model of a rock mass included many fractures. This model is expressed that intact rock resistivity and fracture resistivity are in parallel, and by introducing a coefficient a that varies with the state of fracture, we generalized this model for a rock mass that includes various fractures. To confirm this model experimentally, we used heat to create rock mass models including fractures from granite and diorite. Resistivity was then measured under various pore water resistivities. By regarding the resistivity of these specimens as rock mass resistivity, the results of calculation by this model were compared with the experimental results. When α was 0.3, the calculation results agreed well with the experimental results. Lastly, by using this model, the resistivity of fractured rock mass was calculated for various conditions. The calculations can be used to estimate the resistivity of rock mass containing fractures.View full abstractDownload PDF (3366K) -
Yukinori MATSUKURA1997 Volume 38 Issue 4 Pages 224-231
Published: October 10, 1997
Released on J-STAGE: June 04, 2010
JOURNAL FREE ACCESSDownload PDF (1317K)
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