Q. Q. Yang et al.
4. Conclusions
In this paper, the large flume tests and three large landslides triggered by the Wenchuan earthquake were repro-
duced by DDA, and the following conclusions to be obtained.
(1) DDA was capable of giving considerably satisfactory simulations of the large flume tests, and the differ-
ences between the simulations and measurements were limited to an acceptable range. This consistency de mo n-
strates that DDA effectively described the kinematic behavior, material characteristics, and topographic con-
straint of granular flows in the large flume tests.
(2) Both the simulated and measured velocities in the large flume tests fluctuated due to the propulsion of
subsequent particles to the slowed front by impact. DDA accurately reflected this important phenomenon of the
continuous collision among particles, which was partly responsible for the high mobility and long run-out of
rock avalanches.
(3) The simulated results were highly sensitive to the shape and angularity of granular elements; thus, em-
ploying realistic elements was important for predicting the behavior of granular flows in real situatio ns.
(4) DDA also accurately predicted low velocities of the composite of cubes and gravel, and the agreement
between the simulation and experiment indicates that DDA accurately modeled the energy dissipation caused by
the friction among particles.
(5) Simulation results show that friction coefficient strongly influenced final deposits of large events. The
calculated deposit was only similar to the actual deposit when the apparent friction coefficient, which was de-
termined by field investigation, was used rather than the friction coefficient measured in the laboratory.
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