An experimental program aimed at characterizing the elastic response of roc
k salt under both quasi-static and dynamic conditions has been performed. T
he program includes uniaxial short-term tests and uniaxial creep tests. Dur
ing axial loading, the travel times of longitudinal and transverse elastic
waves propagating in the specimen were simultaneously recorded, together wi
th the strain state. The test results show that in uniaxial, short-term tes
ts, the dynamically determined elastic parameters vary in a similar way as
does the irreversible volumetric strain, i.e. they increase in the compress
ibility domain, are nearly constant in the transition zone from compressibi
lity to dilatancy, and decrease in the dilatancy domain. In creep tests, th
e variation is more complicated: the elastic parameters vary immediately af
ter stress application, but continue to vary slowly in time when stress is
kept constant. Moreover, both G and K increase with time when Et increases
and vice versa (superscript I stands for 'irreversible' and subscript v for
'volumetric'). It appears that the elastic parameters depend on the strain
history or, perhaps on some other type of damage parameters. Thus, the non
-constant elastic parameters governing the 'instantaneous' response in an e
lastic/ viscoplastic constitutive equation that describes compressibility a
nd/or dilatancy and damage (as the total energy released by microcracking d
uring dilatancy) were determined. Copyright (C) 2000 John Wiley & Sons, Ltd
.