T48 Capturing Variability and Uncertainty in Geology for Risk Assessment and Reliability-Based Design (Posters)

Sunday, 27 October 2013
9:00 AM - 6:30 PM
Hall D

RELATIONSHIP BETWEEN PERMEABILITY CHANGE AND NORMAL STRESS IN LARGE DISPLACEMENT SHEAR ZONE OF SAND

Paper number: T48-1
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

  • Sho Kimura Presenting Author
    National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, N/A
  • Hiroaki Kaneko
    National Institute of Advanced Industrial Science and Technology (AIST), Sapporo
  • Takuma Ito
    AIST (now at Research Institute of Innovative Technology for the Earth (RITE)), Kizugawa-Shi
  • Hideki Minagawa
    National Institute of Advanced Industrial Science and Technology (AIST), Sapporo

Abstract

Permeability of sediments is important factors for production of natural gas from Methane-hydrate-bearing layers. There are many small faults near the seafloor observed in the horizontal compressive stress fields due to plate subduction around the forearc basin in the Nankai Trough, where methane-hydrate-bearing sediment is distributed in the seafloor. For a rational evaluation of permeability in the production field, it is important to understand properties of fault zone being a different condition from other layers due to large displacement shear. We investigate the permeability of a specimen experimental fault by ring-shear test under normal stresses of 0.5, 1.0 and 8.0 MPa. The grain size distribution in the shear zone of specimen after shearing at each normal stress level is analyzed by laser scattering type particle analyzer. In the relationship between permeability and porosity, the permeability reduction with decreasing porosity is relatively noted at the normal stress of 8.0 MPa, compared to the relationships at 0.5 and 1.0 MPa. The grain size reduction in shear zone of specimen due to grain breakage during large displacement shearing is clearly recognized at the normal stress of 8.0 MPa. In contrast, the grain breakages are not found at 0.5 MPa. This study is financially supported by METI and Research Consortium for Methane Hydrate Resources in Japan (the MH21 Research Consortium).