Numerical Simulation of Granular Flows in a Large Flume Using Discontinuous Deformation Analysis

Abstract

A long run-out rock avalanche is defined as an extremely rapid, massive, flow-like motion of fragmented rock derived from a bed-rock failure (Hungr et al. 2001). Due to their extraordinary mobility, rock avalanches have been extremely costly in terms of human lives and of engineering developments, and have interested many researchers. Numerical method appears a promising approach for analyzing most of the physical aspects of dry rock avalanches and for predicting the consequence of real events as well (Cundall and Strack 1979; Gonzales et al. 2002; Tommasi et al. 2008). The distinct element method (DEM) and discontinuous deformation analysis (DDA) are the two most popular discrete element methods used to tackle problems dealing with discontinuous rock mass. Limitations of the explicit DEM include its very small step for numerical stability and the use of artificial damping to absorb the energy generated from the relaxation analysis to maintain equilibrium, although some researchers (Calvetti et al. 2000; Valentino et al. 2008) have devoted to appropriately calibrate numerical damping in simulating run-out of granular flows. Shi (1988) claimed that the energy-based DDA can overcome the two limitations of the force-based DEM. Based on its advantages, this paper selected DDA as the analysis method to investigate the behavior of granular flows. In order to acquire confidence in the numerical simulations, it is vital to corroborate them by direct observation and to prove their efficiency. Due to the difficulty of reproducing the complexity of a rock avalanche on a reduced scale, few researchers tackled the problem through an accurate experimental work on physical smallscale models (Valentino et al. 2008). In this spirit, we performed a series of tests to investigate the effects of some factors influencing mass-front velocity and deposit characteristics of granular flows in a large flume. This paper compares DDA simulations and the experimental results in order to validate the efficiency of this numerical method. Q. Yang (&) Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 610031, China e-mail: yangqq_71@126.com