  In order to investigate the relation between the bulk plastic compression
behavior and the evolution of grain size distribution (GSD) due to grain
crushing under high-pressure compression and shear, we performed three types of
loading experiments; single grain crushing (SGC) test, one-dimensional
compression (ODC) test and rotary shear (RS) tests. The materials used are an
angular mountain silica sand and a round river silica sand. The major findings
are summarized as follows: (1) The SGC tests reveal that the Weibull model is
successfully applied with the modulus m=2 for single grain crushing stress. (2)
In the ODC tests, the relation between the applied pressure, p, and the
resulting porosity, n, fits better on a bi-linear model in a log n - log p plot
than in the classical e-log p plot, where e is the void ratio. (3) Both in the
ODC and the RS tests, the GSD converges into a power-law (fractal) distribution
with the exponent (fractal dimension) of about -2.5, which is close to the one
for Apollonian sphere packing, -2.47 (Borkovec et al., 1994). (4) The proposed
recursive pore filling model successfully describes the log n - log p relation
in the ODC test and log n - log relation, where is the shear strain, in the RS
test in a consistent manner.
