  The transmission rules of interparticle forces between granular particles
were analyzed, and a discrete packing model was proposed to calculate the
static pressure at the bottom of granular material confined in a vertical
column. The mechanical analysis and numerical simulation results indicate that
the silo effect is caused by the frictional contacts between border particles
and inner walls, the static pressure at the bottom depends on the external load
initially, and then tends to a saturation pressure (Pn) in an exponential form.
The saturation pressure (Pn) is positive linear related to the container radius
(R) with the same granular matter and stacking manner. The saturation pressure
(Pn) is directly proportional to the particle size (ra), and the increasing or
decreasing characteristic depends on the frictional property of inner walls,
the friction and stacking angle of grains. At last, the predictions of the
aforementioned model are compared with the experimental results from the
literature, and good agreement is achieved.
