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1997 Fiscal Year Final Research Report Summary

Modeling Method for Cracks in Rocks base on the Fractal Structure of the AE Source Distribution

Research Project

Project/Area Number 08651106
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 資源開発工学
Research InstitutionMuroran Institute of Technology

Principal Investigator

ITAKURA Ken-ichi  Muroran Institute of Technology, Department of Computer Science and Systems Engineering, Associate Professor, 工学部, 助教授 (20168298)

Co-Investigator(Kenkyū-buntansha) SATO Kazuhiko  Muroran Institute of Technology, Department of Computer Science and Systems Engi, 工学部, 教授 (30002009)
Project Period (FY) 1996 – 1997
KeywordsAE / Acoustic Emission / Fractal / Cracks / Modeling / AE Source Distribution / Crack Image
Research Abstract

In underground construction it is important to obtain a discontinuities' model of rocks for simulations to evaluate rock stability around the working space and fluid in the rocks. In this study, three kinds of experiments were conducted to develop a more feasible modeling method of cracks in rocks based on AE (acoustic emission) monitoring data and the fractal properties of the AE source distribution.
1.From hydrofracturing tests conducted on cubic-shaped rock specimens, it was found that the AE source distribution during increases in hydraulic pressure was fractal and that the relationship between amplitude and frequency of AE was also fractal. From analysis of the focal mechanisms of AE,it was possible to estimate the principal moment values, principal directions and crack types for events with a relatively large amplitude. However, it was difficult to determine the parameters of focal mechanism in most AE events.
2.From fracture toughness tests using semi-circular disk specimens, it was shown that the 2-D crack and AE source distributions were both franctal. The fractal dimension of the lineaments extracted from a 2-D crack distribution image coincided with the dimension of a linear crack model obtained from AE monitoiring data.
3.A 3-D crack distribution model was constructed using AE monitoring data obtained from uniaxial compression tests on prism-shaped specimens. In this model, the crack was described by a disk, and the fractal dimension of sectional lines that appeared on the surface of a specimen was adjusted to coincide with the dimension of lineaments extracted from a real crack image of the same surface of the specimen by correcting the AE parameters.
It is thought that this new modeling method for cracks in rocks can be directly applied to field studies of underground construction in the future.

  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] Ken-ichi, Itakura: "Fractals on AE Source Distribution andFracture Surface formed by Hydrofracturing ofRock Specimen" Progress in Acoustic Emission. VIII. 305-310 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ken-ichi, Itakura: "AE Activity and Its Fractal Propertieswith Hydrofracturing of Rock Specimens" AE/MA in Geologic structures and Materials. VI. 29-42 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 板倉 賢一: "AE震源分布のフラクタル構造に基づいた岩石内き裂系のモデル化" 資源・素材学会誌. 115・12(予定). (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] ITAKURA Ken-Ichi et al.: "Fractals on AE Source Distribution and Fracture Surface formed by Hydrofracturing of Rock Specimen." Progress in Acoustic Emission. VIII. 305-310 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] ITAKURA Ken-ichi and SATO Kazuhiko: "AE Activity and Its Fractal Properties with hydrofracturing of Rock Specimens." AE/MA in Geologic Structures and Materials. VI. 29-42 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] ITAKURA Ken-ichi et al.: "Modeling of Cracks in Rock Specimen based on the Fractal Struture of the AE Source Distribution." J.of the Mining and Materials Processing Institute of Japan. 115,12 (submitted). (1998)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-03-16  

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