Investigations of the Relations Between Residual Strains, Fabric, Fracture, and Ultrasonic Attenuation and Velocity in Rocks
Final rept. 2 May 1972-1 Jun 1973
TEXAS A AND M RESEARCH FOUNDATION COLLEGE STATION
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Residual strains, fabric, ultrasonic velocity and attenuation, and fracture anisotropy in blocks of Charcoal Granite, Sioux Quartzite, and Berea Sandstone are investigated to determine their causes and effects and the degree to which the attributes can be used to predict fracture anisotropy. Orientations of tensile fractures, induced by point loading oriented discs, are reliably predicted from ultrasonic data in all three rocks with the attenuation data reflecting some not sensitive to velocity. In the granite the fractures are compatible geometrically and probably genetically with the orientations and magnitudes of the residual strains as measured by X-ray diffraction analysis and with several aspects of the fabric. Fractures not parallel to the bedding in the quartzite and sandstone are compatible with residual strains measured by X- rays quartzite and with those detected by strain relief sandstone. Ultrasonic data for these bedded rocks do not correlate with any of the fabric elements studied. The tendency for fractures to propagate along grain boundaries in these rocks suggests minute openings may exist at the boundaries that may influence the fracture and acoustic properties.
- Geology, Geochemistry and Mineralogy
- Civil Engineering