Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
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Volume 50, Issue 5
Displaying 1-5 of 5 articles from this issue
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Original Article
  • Evaluation for Direction Characteristic of Fracture Toughness KIC by SCB Test to Use Core-based Rock Specimens
    Kanemitsu KAWABE, Fumio SUGIMOTO, Tadao IMAI
    2009 Volume 50 Issue 5 Pages 262-272
    Published: 2009
    Released on J-STAGE: March 31, 2013
    DOIhttps://doi.org/10.5110/jjseg.50.262
    JOURNAL FREE ACCESS
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     Quantitative evaluation of crack initiation and propagation is important for examination long-term safety of rock structure. Crack propagation criterion is done based on the concept stress intensity factor and fracture toughness of linear elastic fracture mechanics. Recently, this concept is usually applied in the rock engineering. And, fracture toughness is often assumed to be isotropy. However, it is thought that fracture toughness has directional characteristic when rock is anisotropy by influence of crack condition. There are very few reports about a direction characteristic of fracture toughness and relation with a structural feature in rock. The purpose of this study is to evaluate a direction characteristic of fracture toughness KIC in mode I, tensile or opening mode. The specimen is crystalline granite with physical orthotropic. Details of the consideration are as follows.
     1) Examination for laboratory testing techniques to decide direction characteristic of KIC by SCB test i.e. semi-circular specimens under three-point bending.
     2) Direction characteristic of KIC and the relevance of the structural characteristic of specimen.
     3) Calculation of the maximum crack length in tensile failure.
     In addition, we quantitatively verified mason's experience rule from the result of the direction characteristic of KIC.
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  • Properties of Alkaline Groundwater Seepage from a Tunnel and Its Neutralization Process by Self-Purification Mechanisms
    Takuya AOKI, Toshifumi IGARASHI, Yoshihiro IIO
    2009 Volume 50 Issue 5 Pages 273-279
    Published: 2009
    Released on J-STAGE: March 31, 2013
    DOIhttps://doi.org/10.5110/jjseg.50.273
    JOURNAL FREE ACCESS
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     Groundwater seepage from a tunnel has been alkaline since it was excavated. Leaching experiments with boring core samples around the tunnel and analysis of the groundwater seepage and surrounding river water were conducted to understand the cause of alkaline water and neutralization processes. In addition, geochemical processes were evaluated by using PHREEQE.
     The analytical, experimental and calculation results showed that the alkaline groundwater was primarily caused by the dissolution of calcite contained in the shale and sandstone distributed around the tunnel, and that mixing of the alkaline groundwater with the river water had an insignificant effect on the pH reduction during the dry season. The geochemical calculation suggests that the dissolution of atmospheric carbon dioxide effectively reduces the pH of alkaline seepage from the tunnel. This indicates that the effect of alkaline water can be mitigated by utilizing natural processes. However, it is necessary to quantify the dissolution of atmospheric carbon dioxide into the alkaline seepage.
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  • Quantification of 3 Dimensional Pore Geometry in Porous Rock and Application to Hydraulic Pressure Dependency of Berea Sandstone
    Manabu TAKAHASHI, Masaji KATO, Yukihiko URUSHIMATSU, Hyuck PARK
    2009 Volume 50 Issue 5 Pages 280-288
    Published: 2009
    Released on J-STAGE: March 31, 2013
    DOIhttps://doi.org/10.5110/jjseg.50.280
    JOURNAL FREE ACCESS
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     To quantify the flow-relevant geometrical properties of the pore structure in Berea sandstone, we used the 3DMA method of LINDQUSIT et al. (2000) and verified three-dimensional data for different stress conditions obtained by micro focus X-ray CT. We showed the original CT data and an example of medial axis analysis for the packing of glass beads with 600μm diameters, and confirmed visually the accuracy of the medial axis analysis. We verified the geometric information between pore and throat, such as distributions of pore size, throat size,channel length, and coordination number, by the 3DMA method. In addition, we presented the quantitative characterization of each distribution for intact Berea sandstone and Berea sandstone pressurized to 25 MPa.
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