Prediction of crack density in porous-cracked rocks from elastic wave velocities

Ji Hwan Byun, Jong Sub Lee, Keunbo Park, Hyung Koo Yoon

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    28 Citations (Scopus)

    Abstract

    The stability of structures that are built over rock is affected by cracks in the rock that result from weathering, thawing and freezing processes. This study investigates a new method for determining rock crack densities using elastic wave velocities. The Biot-Gassmann model, which consists of several elastic moduli and Poisson's ratio, was used to determine a theoretical equation to predict the crack density of rocks. Ten representative specimens were extracted from ten boreholes to highlight the spatial variability. Each specimen was characterized using X-Ray Diffraction (XRD) analysis. The specimens were carved into cylinders measuring 50. mm in diameter and 30. mm in height using an abrasion process. A laboratory test was performed to obtain the elastic wave velocity using transducers that can transmit and receive compressional and shear waves. The measured compressional wave and shear wave velocities were approximately 2955. m/s-5209. m/s and 1652. m/s-2845. m/s, respectively. From the measured elastic wave velocities, the analyzed crack density and crack porosity were approximately 0.051-0.185 and 0.03%-0.14%, respectively. The calculated values were compared with the results of previous studies, and they exhibit similar values and trends. The sensitivity of the suggested theoretical equation was analyzed using the error norm technique. The results show that the compressional wave velocity and the shear modulus of a particle are the most influential factors in this equation. The study demonstrates that rock crack density can be estimated using the elastic wave velocities, which may be useful for investigating the stability of structures that are built over rock.

    Original languageEnglish
    Pages (from-to)110-119
    Number of pages10
    JournalJournal of Applied Geophysics
    Volume115
    DOIs
    Publication statusPublished - 2015 Apr 1

    Bibliographical note

    Funding Information:
    This research was supported by a grant from Daejeon University in 2014.

    Publisher Copyright:
    © 2015 Published by Elsevier B.V.

    Keywords

    • Biot-Gassmann model
    • Crack density
    • Elastic waves
    • Porosity
    • Rock specimen
    • Stability

    ASJC Scopus subject areas

    • Geophysics

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