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Volume 46 (2005 - 200･･･
- Issue 6 Pages 311-
- Issue 5 Pages 250-
- Issue 4 Pages 190-
- Issue 3 Pages 115-
- Issue 2 Pages 72-
- Issue 1 Pages 2-
Volume 46, Issue 4
Displaying 1-6 of 6 articles from this issue
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Identification of Water Passage and Detection of Seepage Flow in Low-permeability Rock MassYoji SEKI, Shoichi HISHIDA, Chisato KONISHI, Kazuki NAITO, Yoshio WATA ...2005 Volume 46 Issue 4 Pages 190-197
Published: October 10, 2005
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSHigh-sensitivity heat pulse flowmeter logging was carried out to identify water seepage in a well drilled in Neogene sedimentary rock and pre-Tertiary granitic rock. Water seepage points were identified based on a profile of lost and gained water, which was calculated from the flowmeter logging profile. By using heat pulse flowmeter with a packer assembly detection limit was improved up to 0.03cm/s, which is five times sensitive compared to ordinary heat pulse logging. Most of identified water seepage points agree with open fractures and fissure zones, which were identified by core and bore hole television observation. Based on permeability test, most sections containing identified water seepage points showed higher permeability compared to those without seepage points. Continuous one direction changes of flow speed with small rate observed in Tertiary sedimentary rock and weathered granite are thought to be detected seepage flow in low-permeability rock mass.View full abstractDownload PDF (2120K) -
Kenji HAYASHI, Masanori YAMA, Tetsuro YONEDA2005 Volume 46 Issue 4 Pages 198-206
Published: October 10, 2005
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe Poronai formation area located in Central Hokkaido is mainly composed of Eocene Tertiary marine mudstone. This mudstone can be classified into four different zones depending upon the degree of weathering: a highly weathered, a moderately weathered, a slightly weathered and an unweathered zone. The crystallite size (by XRD) of chlorite in the mudstone shows a variation with the degree of weathering of the mudstone. In addition, the amount of pyrite and calcite in mudstone decreases with increases in the degree of weathering. These mineralogical changes in mudstone may be due to the sulfuric acid produced by pyrite oxidation. Particularly, in highly weathered zones, pyrite and calcite have dissolved and been removed. Weathered mudstone contains cracks, deteriorates in slaking tests and breaks easily. The chlorite mineralogy and the mudstone chemistry may be used as a weathering index for the Poronai mudstone.View full abstractDownload PDF (2478K) -
Satoshi ISHIDA, Kazushi MORI, Takeo TSUCHIHARA, Masayuki IMAIZUMI2005 Volume 46 Issue 4 Pages 207-219
Published: October 10, 2005
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe mechanisms of preferential flow and recharge to groundwater through macropores of sand and gravel aquifer were investigated in the experimental artificial recharge site with recharge pit (2m in diameter and 3m in depth) in Uonuma upland, Niigata Pref. Groundwater dynamics in two experiments of artificial recharge for 10hours/day×5 days were monitored by tracer test, neutron moisture logging and radon concentration measurements in groundwater near groundwater table. Tracer test in the first experiment showed that the groundwater table started to increase after 2.5 hours of artificial recharge and the tracer was detected after 3.5 hours and the concentration of the tracer peaked after 9.5 hours. The second experiment showed as follows. The neutron moisture logging revealed that the parts of increasing water contents with several percent in unsaturated zone gradually moved from shallow zone to deep zone and the downmovement rate of increasing water contents was 0.9m/h in a shallower zone than 6m in depth, and was 2.6m/h in a deeper zone than 6m in depth. The difference of the rates may relate with the difference of the saturated hydraulic conductivity values of two zones. The decreasing radon concentration near the groundwater table gradually occurred from 7 hours after artificial recharge, while the increasing of groundwater level began from 6 hours after artificial recharge. The down-movement rate of preferential flow is three times bigger than the rate presumed from the saturated hydraulic conductivity values. It was assumed that the groundwater level started increasing when the tracer and the recharge water through macropores reached a capillary zone.View full abstractDownload PDF (3395K) -
Weiren LIN, Tadanori GOTO, Toshiaki NAKAMURA, Hitoshi MIKADA2005 Volume 46 Issue 4 Pages 220-226
Published: October 10, 2005
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSElectrical resistivities of two mudstone specimens were measured under high confining pressure until about 30MPa and under constant pore pressure at 0.6MPa using a new resistivity measurement system. It is consisting of a pressure vessel of a triaxial compression test apparatus and a resistivity measurement device used for the conventional measurements under atmospheric pressure. The used rock block sample was taken from a mud volcano situated above Kumano Basin of where the depth is about 2, 000m from sea surface. The resistivities of the rock determined by this system have a relatively high reproducibility. In addition, this measurement method employing a rubber jacket and loading some confining pressure can accurately and easily keep the water content of specimen at a constant during the measurement. Thus, the method can more properly prevent the superfluous water existing between the surface of specimen and the jacket than the conventional method by which the specimen was set in a box or laboratory in unjacketed state. As a consequence, it results in that the resistivity may be determined more accurately. The measurement results of the tow rock specimens saturated by sea water used in this study showed that the resistivity increased as the effective confining pressure was elevated. If the influences of pore pressure to the conductive property of clay minerals can be neglected, the fact that there was not a distinct change of gradient of resistivity-pressure curves on loading process suggests that the maximum historical stress of the rock may be larger than 30 MPa, which corresponds a depth of about 2km beneath the seafloor. By comparison between intact and cracked specimens, it was clear that the effect of confining pressure on the resistivity for the cracked specimen was more significant than that of intact specimen due to the closuring of the cracks under pressure loading.View full abstractDownload PDF (1777K) -
Yukiyasu FUJII, Takato TAKEMURA, Manabu TAKAHASHI, Weiren LIN, Shunji ...2005 Volume 46 Issue 4 Pages 227-231
Published: October 10, 2005
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSUniaxial tensile fractures parallel to each anisotropic plane in Inada granite has been investigated by direct observations and under microscope. Many part of the fractures split the rock-forming mineral grains, and only about 10 percent of them follow grain-boundary cracks. The fracture surface parallel to the rift plane have almost same constituent mineral ratio as the parent rock. However the fracture, parallel to the grain and hardway planes, prefer feldspar grains and cut across less quartz than the parent rock. It's especially remarkable in the fracture parallel to the hardway plane. The different surface mineral ratios of fractures parallel to each plane are caused by preferred orientations and distributions of microcracks in quartz and feldspar.View full abstractDownload PDF (1441K) -
Ryoji FURUE, Teruki IWATSUKI, Katsuhiro HAMA2005 Volume 46 Issue 4 Pages 232-236
Published: October 10, 2005
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSHydrochemical investigation of deep groundwater by using deep borehole requires various technical tasks through drilling borehole, sampling and analysis of groundwater to estimate reliable groundwater chemistry. For instance, the groundwater is contaminated by drilling water during drilling, mix with groundwaters in different aquifers, and react with atmosphere during sampling and analysis. We report the reality of hydrochemical investigation and the procedures for quality control in the investigation. Many kinds of investigation showed that the influence of drilling fluid contamination and mixture of groundwaters of different aquifers can be evaluated by managing the concentration of fluorescent dye and solutes in drilling fluids. In addition, it is necessary to measure in-situ pH and Eh groundwater to prevent reactions between groundwater and atmosphere, and degassing by pressure releasing.View full abstractDownload PDF (1072K)
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