AN ANALYSIS OF SHOCK-INDUCED DAMAGE IN ROCKS
He Hongliang;Thomas J.Ahren;Allan M.Rubin(Laboratory for shock Wave and Detonation Physics,Southwest Institute of Fluid Physics,P. O. Box 523,Chengdu,610003)(Lindhurst Laboratory of Experimental Geophysics, Seismological Laboratory, California Institute o
A definition of shock damage parameter,D=1-(c_p/c_(po))￣2,is propased for rock-like brittle materials,where c_(po) and c_p are elastic longitudinal wave velocities of unshocked andshocked materials,respoctively. Fullowing this definition,damage distribbutions in shocked Gabroand Limestone were experimentally miasured,,in which c_p values were measured by an ultrasonictransmission technique,For shock damaged gabbro, the characteristics of elastic longitudinal wavevelocity and com pressive strength under quasistatic uniaxial loading are also studied.In all thetested samples(with different initial damage parameter) a large increment of elastic velocities areobserved under the stresses ranging from 0 to 50 MPa. We suspect this behaviour is due to a mi-crocracks(induced by the shock loading ) re-closing process.After microcracks re-closing,theshocked gabbror with initial damage D_00.1 have nearly the same elastic wave velocities andcompressive strengthes as the unshocked ones.For the samples with initial damage D_00.1 ,how-ever.their values are much reduced and could not be rebounded to the intrinsic values.