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Applications of Discrete Element Method 311

those located very close to the shear plane. Particle movements in the upper box dis-
played significant vertical dilation. The simulations based on irregular particles showed
the same trend as the experimental observations, while those based on spheres showed
very erratic particle translational movements.

Particle Kinematics in the Shear Zone
To evaluate the predictions of the shear zone by the two DEM models, the micro-kine-
matics including magnitudes of particle displacements and magnitudes of particle rota-
tions in measuring columns (refer to the location of the monitoring system; the colored
sphere columns in Figure 9.19) were quantified. For simplification, only particle rota-
tions are presented in Figure 9.21a (for spheres), Figure 9.21b (for irregular particles)
and Figure 9.21c (for measured). In Figure 9.21a, the spherical particle rotations are er-
ratic. Large particle rotations occurred not only near the shear plane but also at other
areas. To summarize, no significant shear zone has been formed in the simulation based
on spheres. In Figure 9.21b, the irregular particle rotation is small at the upper and

140.00
140.00
120.00 120.00 colume A
Height of specimen (mm) 80.00 column A Height of specimen (mm) 80.00 colume C
column B
100.00
100.00
60.00
60.00
40.00
20.00
20.00 column B 40.00
column C
0.00
0.00
0.00 0.20 0.40 0.60 0.80 1.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20
Particle rotation (mm) Particle rotation (mm)
a) Particle rotation distribution b) Particle rotation distribution
along the height of the specimen, along the height of the specimen,
simulation using spherical particles simulation using irregular particles
140.00
120.00
100.00
Height (mm) 80.00
60.00
40.00 column A
column B
20.00
column C
0.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20
Particle Rotation (rad)

c) Measured particle
rotation distribution along
FIGURE 9.21 Particle rotational movement. the height of the specimen