Wk. Zietlow et Jf. Labuz, MEASUREMENT OF THE INTRINSIC PROCESS ZONE IN ROCK USING ACOUSTIC-EMISSION, International journal of rock mechanics and mining sciences, 35(3), 1998, pp. 291-299
Citations number
14
Categorie Soggetti
Geochemitry & Geophysics","Mining & Mineral Processing
Laboratory specimens with a smooth boundary (no notch) were fabricated
from four different rock types (grain sizes from 0.1-10 mm) and were
tested in three-point bending. The locations of acoustic emission that
occurred around peak load were used to characterize the dimensions of
the region of localized microcracking, the so-called intrinsic proces
s zone. The size of this zone was found to vary significantly between
the rock types, but was not found to vary significantly for different
size beams of the same material, An approximately linear relation was
found between the width of the intrinsic process zone and the logarith
m of the grain size. An explanation of size effect evolves naturally b
y considering the intrinsic process zone as a material characteristic.
Two different models were used to analyze stress at failure. The firs
t treated the intrinsic process zone as a mathematical crack, an infin
ite stress raiser, from which a K-IC value was calculated. The second
model assumed the intrinsic process zone was a cohesive notch, a finit
e stress raiser, from which the theoretical tensile strength was defin
ed. The second method seemed somewhat better at predicting size eject
on nominal peak stress. (C) 1998. Published by Elsevier Science Ltd.