SHEARING OF GRANULAR materials causes rearrangement of the granular st
ructure which induces irreversible volume decrease and shear strain, i
n addition to reversible strain. The model adopted describes the rever
sible compression and shear by hypoelastic laws, and the irreversible
compaction and shear by evolutionary laws. The latter are differential
relations defining the progress of irreversible strain as an appropri
ate time-independent monotonic loading parameter increases, which inco
rporate dependence on the current state, and which prescribe a directi
on for the irreversible shear strain increment. The model is described
by four material functions and two material constants, and has been s
hown to determine valid initial response to applied shear stress. We a
pply the model to the compaction of a granular material in uni-axial s
train, which is described by two simultaneous differential equations f
or the axial stress and compaction with the axial strain as independen
t variable, together with algebraic relations for the pressure and lat
eral stress. The equation forms for loading-increasing axial stress-an
d unloading-decreasing axial stress-are distinct. Reformulation as dif
ferential equations for the pressure and the principal stress differen
ce shows that the pressure derivative depends only on two of the mater
ial functions and one constant. The axial strain and lateral stress me
asured during a complete load-unload cycle on a sand determine the pre
ssure and stress difference derivatives which are correlated directly
with the model differential relations. Two material functions and one
constant are determined by an optimization procedure from the complete
load-unload pressure data, then the remaining two functions and const
ant from the stress difference data. Solution of the resulting model d
ifferential equations reproduces accurately the axial strain and later
al stress variations during the experimental loading cycle. In additio
n, model predictions for load-unload cycles to different maximum stres
ses are illustrated, and an approximate common feature of the differen
t unloading curves is determined. This is a useful property for the ap
plication of the model to the propagation of a load-unload pulse where
the amplitude progressively decreases due to the unloading interactio
n.