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Kikuyama H.,A TiC Co. | Ota S.,Kawasaki Geological Engineering Co Ltd
ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 | Year: 2014

The results of drill core observation are among the most important basic data for geological survey; however, these results tend to include subjective aspects, because the core sample is qualitatively evaluated through macroscopic observation by engineers with different skill levels. Similarly, the classifications of strata, rock hardness and degree of weathering, which are derived from the results of drill core observation, tend to be subjective and tend to depend on the abilities of the engineers involved in determining them. These subjective aspects sometimes result in differences in evaluations that make it difficult for others to understand the basis for evaluation. This study aimed at adding quantitative indexes to core observation. Measurements of magnetic susceptibility and color were done for drill cores of igneous rocks and sedimentary rocks. To examine the validity of the quantitative indexes, the results of classification of strata, rock hardness and weathering from the quantitative method were compared with those from conventional core observation. Magnetic susceptibility and color were measured using portable meters, which enabled onsite measurement. Examinations revealed that the differences in measured magnetic susceptibility and color correspond to the differences in strata, lithofacies, rock hardness and degree of weathering. In measurements using a magnetic susceptibility meter and a color meter, it was possible to qualitatively determine the borders between different types of rock, even when it was difficult to determine the border by macroscopic observation because the changes in the borders were gradual. Using measurements of magnetic susceptibility and color in combination made it possible to examine the results by comparing and supplementing the results from the two measurement methods. Measurements of magnetic susceptibility and color of drill cores showed that it was possible to use these measurement results as useful quantitative indexes for classifying strata, lithofacies, rock hardness and degree of weathering, for comparing multiple cores, which is conventionally done by visual inspection, and for determining the landslide slip surface. © 2014 by Japanese Committee for Rock Mechanics. Source


Inagaki Y.,Public works research institute | Tsukamoto M.,Kawasaki Geological Engineering Co Ltd | Sasaki T.,Public works research institute | Kawasaki S.,Hokkaido University
ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 | Year: 2014

In taking measures to prevent damage to existing structures by liquefaction, new techniques to improve the ground immediately under an existing structure without dismantling or removing the structure are currently being sought more enthusiastically than before. As ground improvement techniques using microbial metabolism to promote the relatively slow solidification of the ground, these are expected as suitable techniques for ground improvement under existing structures. Our research focused on the microbial carbonate precipitation (MCP), in which calcium carbonates precipitated from reactions between carbon dioxides and calcium sources by microbial metabolism binds soil particles and solidifies soil. In our research, sands solidified by MCP were subjected to cyclic triaxial tests to check their deformation characteristics. In addition, a dynamic centrifugal model test was conducted to check the effect of liquefaction countermeasure when the entire ground was solidified. © 2014 by Japanese Committee for Rock Mechanics. Source


Hitomi T.,Obayashi Corporation | Sasakura T.,Kajima Corporation | Yamaura M.,Chiyoda Corporation | Tozawa M.,Asano Taiseikiso Engineering Co. | And 3 more authors.
Energy Procedia | Year: 2013

For geological storage, as the small-scale distributed emission systems, CO2 micro-bubble storage (CMS) system may be suitable. To validate the feasibility of the CMS system, a numerical analysis was carried out. For the injection method and the targeted depth defined above, a unit comprising an injection well and four water pumping wells was modeled, The study showed a possibility of stable storage of CO2 in solution under the conditions of temperature, pressure and water chemistry at depths of 300 to 500 m, as long as full dissolution of CO2 gas with micro-bubbles is ensured. Source


Shidahara T.,NEWJEC Inc. | Okumura T.,Engineering Advancement Association of Japan | Miida H.,Engineering Advancement Association of Japan | Shimoyama M.,Obayashi Corporation | And 4 more authors.
Energy Procedia | Year: 2013

Although CO2 underground geological storage has been proposed, it is important for smaller emission sources to develop a local and distributed small-scale CO2 underground storage system, too. To examine if it is feasible, CO2 micro-bubble storage (CMS) as one of the small-scale systems has been studied. As part of this ongoing study, the following two subjects were examined: 1) geological conditions appropriate to the CMS and its storage potential in Japan; and 2) outline cost estimation of the CMS. Results of this study showed that the CMS system could well be feasible technically and economically. Source


Abe T.,Nippon Expressway Research Institute Company Ltd | Tsukamoto M.,Kawasaki Geological Engineering Co Ltd | Yokota S.,Nippon Expressway Research Institute Company Ltd | Tayama S.,Nippon Expressway Research Institute Company Ltd
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability | Year: 2015

Expressway embankments have collapsed in many locations in Japan recently because of torrential rains and earthquakes striking the areas. Because the soil from collapsed embankments contains much water, we have assumed that penetrating rain and groundwater affected the embankments, in some way, and led to the collapse. To reinforce the slopes and prevent such disasters, we have dug slits where are excavated at the foot of the slope and filled with crushed stones to reduce the water content ratio of the slope. To verify the effectiveness of this measure, we have conducted the following two tests. First, we conducted laboratory tests, changing the water content ratio, to examine the changes in the strength characteristics of the embankment soil. This test confirmed that soil strength weakens as the water content increases, even if compaction of the soil remains the same. For the second test, we made a 1/50-scale model embankment and carried out large-scale dynamic centrifugal force loading tests to verify the reinforcement effects of this measure. The test confirmed that embankments reinforced with the drainage works held down deformation to half of that of embankments which were not reinforced. Source

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