Q-factor by spectral ratio technique for strata evaluations

The laboratory estimated quality factor 'Q', a function of acoustic wave sp eed (V), amplitude (A) and frequency (f), were chosen for in situ strata ev aluation of rocks of the right bank canal of upper Wardha, Maharashtra, Ind ia, using the spectral ratio technique. Eleven core samples of compact, amy gdaloidal, and vesicular basalts, were characterized by their Q values. The Q-factor determined using the spectral ratio technique with centre frequen cy of 500 kHz, is found to result in differing values for compact, amygdalo idal, and vesicular basalts over ranges 10-14, 4-6, and 2-4, respectively. The specimens belonging to amygdaloidal and vesicular basalts with secondar y minerals and calcareous intrusions in the vesicles have a very low Q valu e and a very low yield of rock mass that is not proportionate to the energy generally used in blasting operations. A correlation of Q = 0.26RQD(%) + 3 .68 between the laboratory-measured Q value and in situ rock quality design ation (RQD) (data obtained from the recovery of the exploratory borehole co re samples) provides a useful means of understanding geological strata in r ock mass recovery evaluation. The lower Q values implied higher energy requ irements for effective excavation of the rock masses. (C) 2000 Elsevier Sci ence B.V. All rights reserved.