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Mechanical Properties of Shock-Damaged RocksStress-strain tests were performed both on shock-damaged gabbro and limestone. The effective Young's modulus decreases with increasing initial damage parameter value, and an apparent work-softening process occurs prior to failure. To further characterize shock-induced microcracks, the longitudinal elastic wave velocity behavior of shock-damaged gabbro in the direction of compression up to failure was measured using an acoustic transmission technique under uniaxial loading. A dramatic increase in velocity was observed for the static compressive stress range of 0-50 MPa. Above that stress range, the velocity behavior of lightly damaged (D(sub 0) less than 0.1) gabbro is almost equal to unshocked gabbro. The failure strength of heavily-damaged (D(sub 0) greater than 0.1) gabbro is approx. 100-150 MPa, much lower than that of lightly damaged and unshocked gabbros (approx. 230-260 MPa). Following Nur's theory, the crack shape distribution was analyzed. The shock-induced cracks in gabbro appear to be largely thin penny-shaped cracks with c/a values below 5 x 10(exp -4). Moreover, the applicability of Ashby and Sammis's theory relating failure strength and damage parameter of shock-damaged rocks was examined and was found to yield a good estimate of the relation of shock-induced deficit in elastic modulus with the deficit in compressive strength.
Document ID
19970013371
Document Type
Reprint (Version printed in journal)
Authors
He, Hongliang (California Inst. of Tech. Pasadena, CA United States)
Ahrens, T. J. (California Inst. of Tech. Pasadena, CA United States)
Date Acquired
August 17, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Int. J. Rock. Mech. Min. Sci. & Geomech. Abstr.
Volume: 31
Issue: 5
ISSN: 0148-9062
Subject Category
Geophysics
Report/Patent Number
NAS 1.26:203524
NASA-CR-203524
Distribution Limits
Public
Copyright
Public Use Permitted.
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