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Volume 39 (1998 - 199･･･
- Issue 6 Pages 486-
- Issue 5 Pages 414-
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Volume 39, Issue 6
Displaying 1-7 of 7 articles from this issue
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Mitsuyoshi IKEDA, Atsuo TAKEUCHI, Kinya MIURA, Hiroharu MATSUEDA, Tada ...1999 Volume 39 Issue 6 Pages 486-499
Published: February 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe Satsunai river fan and the adjacent Sarubetsu river fan located in the southern part of the Tokachi plain, Hokkaido, together form two drainage basins in a composite fan. Groundwater flow from the Satsunai river to the Sarubetsu river fan was previously believed to be negligible. The present study revealed, however, the existence of a buried valley corresponding to the old Satsunai river lying beneath the Sarubetsu river fan. Environmental tracer techniques such as measuring 0.8m depth ground temperature, making use of the altitude effect of stable isotopes of water and the dissolved ions, groundwater flow net and water balance analyses all showed more than lm3/s leakage from the Satsunai river. This represents an important contribution to the groundwater flow system of the Sarubetsu river fan.
Recently, a large project requires an environmental assessment of the groundwater flow system scale. Therefore, the present study suggests the importance of using environmental tracers not only for scientific purposes, but also for civil engineering applications.View full abstractDownload PDF (3113K) -
Masahiko OSADA, Tadashi YAMABE, Ryunoshin YOSHINAKA1999 Volume 39 Issue 6 Pages 500-510
Published: February 10, 1999
Released on J-STAGE: June 23, 2010
JOURNAL FREE ACCESSInitial distribution of microcracks in Inada granite is examined by microscopic observation of thin sections cut in three directions perpendicular to each other. The result shows that the distribution of microcracks is very imhomogeneous in spatial distribution. Namely, though the average of grain size is about 2 mm, main forming minerals such as quartz, feldspar and biotite are dispersedly distributed, so that they make clusters which distance are about 5 to 10 mm and independent of the cutting direction. Therefore the microcracks is also dispersedly distributed because most of microcracks are observed in quartz grains. This distribution of microcracks must affect on the mechanical and hydraulic properties of this rock.
The frequency distributions such as crack orientation and crack length are calculated by image analysis of microcracks which lengths are longer than 0.1 mm. The distribution of crack orientation corresponds with the orientation of three splitting planes which are observed in the quarry of Inada granite except that the orientation of grain plane in the quarry is different by 10 to 20 degrees from the orientation of mode in crack orientation. In view of orientation of crack distribution, this granite is not perfectly orthotropic material. This property plays an important role of ultimate fracturing of the specimen under triaxial compression particularly when the specimen is loaded in the direction vertical to the rift plane. On the other hand, the frequency distributions of crack lengths are almost the same in shape in spite of the cutting direction.View full abstractDownload PDF (4305K) -
The Weathering Rates of Mudstone on Old Unlined Tunnel Walls and the Bacterial Effects on ItTakahiro OYAMA, Masahiro CHIGIRA, Naoya OHMURA, Kazuhiro SASAKI, Toru ...1999 Volume 39 Issue 6 Pages 511-523
Published: February 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSWeathering of soft mudstone walls of unlined tunnels that were excavated several decades ago in the Kakinokidai Formation (middle Pleistocene) and the Kiwada Formation (lower Pleistocene) of the Kazusa Group of Chiba prefecture in Japan was investigated by mineralogical, chemical, physical and biological methods. Sulfuric acid was generated by pyrite oxidation and calcite dissolved by sulfuric acid, and gypsum crystallized at the surface of wall. The weathering rates (rates of movement of oxidation fronts) were explained by diffusion of oxygen from the wall surface. The relationship of depth of oxidation front (lcm) and elapsed years since excavation (tyear) was expressed by l=R√t with considering the diffusion of oxygen into the rock. The R values were 5 on sandy mudstone of middle Pleistocene, 2-4 on mudstone of middle Pleistocene and 0.3 on mudstone of lower Pleistocene. The diffusion coefficients of oxygen (De) calculated by the chemical compositions corresponding to the above three kinds of rocks were 10-5cm2/s, 10-7-10-5cm2/s and 5×10-8cm2/s, respectively. De may depend on coefficients of air permeability of rocks that correlate closely with coefficients of the water permeability (K). The relationship is log Decm2/s=0.91logKcm/s-0.71. Bacteria were slightly found at a part of the oxidized zone. Size of rock pore and its water quality may be hardly fitted for bacterial habitation.View full abstractDownload PDF (2230K) -
Qi You ZHOU, Jun SHIMADA, Akira SATO1999 Volume 39 Issue 6 Pages 524-532
Published: February 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSTo apply Electrical Resistivity Tomography (ERT) in monitoring temporal and spatial variation of soil water, by using finite-element method as forward modeling, we proposed a patching algorithm of inversely calculating 3D soil resistivity in this paper. From finite-element forward modeling, sensitivity calculation to formation of initial model parameters, we systematically described the inversion calculation process of using patching algorithm. At the end, we gave out results about two numerical experiments and one field measured data inversion to illustrate the effectiveness of the algorithm. By patching algorithm, the initial soil resistivity model is step by step modified to make the calculated potential approximate that measured. Each measurement event (group of pole-pole array measurements which have same current electrode and input current) composes a step of modification to the model. This algorithm is appropriate when the data number for one measurement event is quite less than the parameter number of the model and the measurement event number varies with the equipment capacity or prospecting objectives, and even when the resistivity changes with time. Numerical experiments and field measured data inversion indicated the effectiveness of the inverse algorithm, but also revealed the difficulty of completely inversely calculating out the 3D subsurface soil resistivity only by using the data measured at the soil surface.View full abstractDownload PDF (3950K) -
Weiren LIN, Manabu TAKAHASHI, Kaoru NISHIDA, Ming ZHANG1999 Volume 39 Issue 6 Pages 533-539
Published: February 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (1314K) -
Takashi SAKURAI1999 Volume 39 Issue 6 Pages 540-544
Published: February 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (1582K) -
1999 Volume 39 Issue 6 Pages 558
Published: 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (72K)
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