Journal of MMIJ
Online ISSN : 1884-0450
Print ISSN : 1881-6118
ISSN-L : 1881-6118
126 巻 , 3 号
選択された号の論文の7件中1~7を表示しています
総説
  • 深川 良一, 酒匂 一成, 里見 知昭
    2010 年 126 巻 3 号 p. 49-57
    発行日: 2010/03/25
    公開日: 2011/04/29
    ジャーナル フリー
    In Japan, slope disaster frequently occurs during rainy season, thus it is very important to construct a warning system to predict possibility of slope failure due to rainfall. The purpose of this research is to construct such the system using real time field measured data, in-situ tests, laboratory tests, and numerical models. We have established a field monitoring system to measure rainfall intensity, pore-water pressure, temperature, etc., on a slope behind an important cultural asset in Kyoto City since July 2004. Ground displacement has also been measured since May 2006 using optical fiber sensors (B-OTDR) , and additional measuring points were implemented in order to investigate more details of water behavior in the study slope. In this paper, outline of the above warning system and the field monitoring system are explained, and the in-situ seepage behavior is considered based on the field measurement data. Monitoring results of ground displacement during rainfall in March 2008 are also presented, and the influences of rainfall on the ground displacement are also discussed. Finally, the indoor and outdoor test results of the wireless sensor network system, which employed multipoint monitoring, is examined through this paper.
論文
  • 石田 毅, 深堀 大介, 石田 基, 佐藤 亮介, 村田 澄彦, 小野塚 重信, 大瀬戸 一仁, 山本 晃司
    2010 年 126 巻 3 号 p. 58-63
    発行日: 2010/03/25
    公開日: 2011/04/29
    ジャーナル フリー
    AE (acoustic emission) events have been monitored with water injection in enhanced oil recovery and in a fractured reservoir of oil and gas fields to detect reservoir behavior with pore pressure increase. Since the AE events are induced by various causes, it is important how to obtain useful information from the monitored AE events. Thus, in this research, we monitored AE events in a tri-axial experiment of Berea sandstone under control of pore pressure, to simulate AE monitoring in oil and gas fields.
    The results have demonstrated the followings.
    (1) The failure that is induced by pore pressure increase and accompanies the AE events could be explained and predicted by Mohr-Coulomb's failure criterion and Terzaghi's effective stress theory.
    (2) Places where failures are induced could be clarified by source location of the monitored AE events.
    (3) Fault plane solutions of the AE events are consistent with the directions of the induced macroscopic fracture plane and the stress condition applied in the experiment.
    It could be concluded that AE is useful to monitor reservoir behavior with pore pressure increase, although further investigations from various aspects are needed.
  • 雷 鳴, 大久保 誠介, 福井 勝則, 羽柴 公博
    2010 年 126 巻 3 号 p. 64-71
    発行日: 2010/03/25
    公開日: 2011/04/29
    ジャーナル フリー
    In order to express the behaviour of fractured rock in compaction test with a constitutive equation, some basic discussions were attempted. The variable-compliance-type constitutive equation was employed in this study. The constitutive equation can express the failure process of rock, which has been well proved heretofore. In the constitutive equation, it is assumed that the rock fails at a rate which depends on stress severity.
    In this study, the concept of stress severity Sv was expanded to the stress state where Sv took negative value and healing parameter Hp = -Sv was introduced. The constitutive equation was also modified assuming that fractured rock is gradually compacted or healed at a rate which depends on healing parameter. According to the results in this study, it can be said that the equation expresses the behaviour of the fractured rock when the compliance becomes smaller in the compaction test. In addition, to some extent, it was also possible to explain the increase of the principal stresses with time. Though further discussions are essential in the future definitely, it can be said that the modified variable-compliance-type constitutive equation showed much potential for simulating the behaviour of fractured rock in compaction test and interpreting strength recovery of rock in loosen zone or EDZ around an underground structure.
  • 高田 迪彦, 藤井 義明
    2010 年 126 巻 3 号 p. 72-77
    発行日: 2010/03/25
    公開日: 2011/04/29
    ジャーナル フリー
    The effect of stress on free surface dissolution of NaCl was investigated. Stress and elastic constants near the {001} surface of NaCl crystal were calculated using a classical molecular dynamics simulation. The normal stress in the first layer of the free surface was calculated as approximately 2.25 GPa (tension) on the assumption that the bulk stress was 0. The elastic constants of the first layer were also different from those of the bulk. Based on the results, it is estimated that molar Gibbs free energy of the first layer will increase by tension, and decrease by compression. Namely, NaCl crystal is expected to become easier to dissolve by tension and harder to dissolve by compression. This qualitatively coincides with the experiments on NaCl free surface dissolution under loading.
  • 伊藤 俊秀, 別所 昌彦, 陳 友晴, 野村 泰稔
    2010 年 126 巻 3 号 p. 78-83
    発行日: 2010/03/25
    公開日: 2011/04/29
    ジャーナル フリー
    It is important to control the calcium or phosphorus concentrations in quarry products such as limestone. In some quarries in Japan, limestone blocks with low grade concentrations are blended with limestone blocks with high grade concentrations to satisfy the product quality requirement. In this study, some simulation methods were considered to develop the best mining plan for such quarries.
    A quarry was divided into small rectangular blocks and a mining plan was considered as an optimal combination problem of these blocks. All possible combinations of limestone blocks were examined by a dynamic programming method, and almost the best solution was determined for a set of 600 blocks scale. However this method required large processing time for large-scale quarry; for example, it would be required 6,800 h for 2,400 blocks. On the other hand, genetic algorithm requires less than 6 h for 2,400 blocks, and it generates reasonable solutions whose quality rate is 80% of that generated by the dynamic programming method. Thus, to develop a long-term mining plan for large quarries, first genetic algorithm must be used to obtain approximate solutions, and then, the best solution should be determined by a dynamic programming method for short-term mining plan.
    Moreover, the grade adjustment of the opposing limitations on calcium and phosphorus concentrations in limestone blocks, that is, the permitted calcium concentration has a lower limit whereas permitted phosphorus concentrations has an upper limit, was tried to solve. Finally, these methods can be easily applied to metal mining too.
  • 藤井 孝志, 林 宏飛, 佐藤 善之, 菅井 裕一, 佐々木 久郎, 猪股 宏, 橋田 俊之
    2010 年 126 巻 3 号 p. 84-94
    発行日: 2010/03/25
    公開日: 2011/04/29
    ジャーナル フリー
    Sorption isotherms, which describe CO2 storage capacity of rocks, are important for estimating CO2 sequestration potential of geological reservoirs. This study examined CO2 sorption capacity of Kimachi sandstone and Iidate granite in the CO2 rich dense phase, the condition of which is expected to occur mostly in the course of CO2 injection into geological reservoirs because of the displacement of formation water by CO2 pressurization in geological reservoirs as storing CO2 into aquifers, at geological temperature and pressure. CO2 sorption measurements were conducted using both volumetric and gravimetric methods at temperatures of 33∼200°C and pressures up to 20MPa. It was found that Kimachi sandstone and Iidate granite were capable of sorbing CO2 into their internal structures. At 50°C, the amount of CO2 sorption reached the maximum value of 1.4 mmol/g (= 31.4 scc/g) for Kimachi sandstone and 0.7 mmol/g (=15.7 scc/g) for Iidate granite, respectively. Comparison among model predictions (monolayer adsorption, solubility and pore-filling) suggests that the sorption of CO2 onto rock minerals may contribute to a significant portion of the CO2 storage capacity in the course of CO2 injection.
    This investigation points out the significance of CO2 sorption onto rock minerals for the possible mechanism in CO2 geological storage.
  • 湯本 徹也, 白鳥 寿一, 中村 崇
    2010 年 126 巻 3 号 p. 95-102
    発行日: 2010/03/25
    公開日: 2011/04/29
    ジャーナル フリー
    Hard disk drive (HDD) is a major device in information appliances. Market of HDD has expanded for over 10 years. Though many kinds of metal are used in HDD, especially some minor metal in printed circuit board (PCB) and rare-earth elements in voice coil motor (VCM) magnet, they haven't been recycled enough. In order to gain basic information of recycling of end-of-life HDD, inventory of HDD has been investigated by measuring weight and metal content of PCB and rare-earth magnet in HDD. Weight of PCB and VCM magnet has decreased gradually by improvement of technology of PCB design and magnetic materials, nevertheless disassembling efficiency hasn't been improved for 10 years because of few change in basic structure of HDD. It was shown that contents of some minor metals (Ta and Pd) and harmful elements (Pb, Sb, Br) in PCB have decreased because of their rising value or material regulations such as RoHS. Content of Nd, Pr, Tb and Dy in VCM magnet was investigated by chemical analysis. Although only dysprosium was mainly used till 2000 for the improvement in coercivity of a magnet, Tb has also come to be used as an alternative element in 2001 and afterwards. It was suggested by calculation that magnet of 1,492ton and PCB of 4,012ton remain at 2008 as the in-use stock in Japan. It is desired to improve the structure of collection and pretreatment process of end-of-life HDD.
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