Ohnaruto Bridge, one of the Honshu Shikoku connecting bridge, is a suspension bridge of 876m center span located in Naruto Straits. Foundation rock consists of the Cretaceous sandstone and shale which have remarkable stratifications of monoclinic structure dipping to SE at 45°-50°. Engineering propertes of the submarine foundation rock were researched by many core drillings, in-situ load tests in the holes and geophysical loggings. Estimation for the strength of rock mass was performed mainly by the deformation modulus of in-situ load test and total point method which was attempted for the stratified rock of Ohnaruto Bridge foundation. This method is a kind of synthetic classification of rock grade evaluating characteristics of drilled core, such as hardness, shape, crack width and nature of cracks.
The characteristic altered biotites are observed in the weathered granite at eastern part of Tottori prefecture, Japan, From the mineral assemblage, they are classified into following types: (1) Kaolinite+interstratified Chlorite-Vermiculite (2) Kaolinite+Vermiculite + interstratified Chlorite-Vermiculite (3) Kaolinite+Chlorite+Vermiculite+ interstratified Chlorite-Vermiculite. The hydroxy-aluminium interlayer may form in the all of discrete vermiculite and interstratified vermiculite. They are different from the mineral assemblages of weathered biotite. Judging from the mode of occurrence, they were formed from the altered chloritic biotite under the weathering condition. They gives a evidence of hydrothermal alteration before weathering of the parent rock.
The present paper is mainly concerned with the dissolved major constituents of natural waters in landslide areas. The following items are discussed: (1) Relation between chemical composition and discharge of ground waters, (2) Partial pressure of dissolved carbon dioxide gas of ground waters, and (3) Mineral-water interactions. And the author has emphasized a geochemical method for clarifying the role of weathering processes and landslide phenomenon.