Experimental study on the collapse of wet granular column in the pendular state

The collapse of wet granular columns in the pendular state is experimentally investigated, where the effects of the initial aspect ratio, the water content, and the particle size on the dynamics and the deposit of collapsing material are mainly considered. Three typical regimes are observed in our experiments, and a phase diagram is then proposed for describing different flow states. Furthermore, the velocity field of collapsing material exhibits distinct evolving features in two collapse regimes, and the transition between different regimes is also discussed, where the capillary effect plays different roles. On this basis, the influence of the water content on the flow duration and the final deposit morphology of collapsing material are further analyzed. Finally, a simplified theoretical model is put forward, which has been proved to be able to describe the dependence of the runout distance on the particle diameter in the collapse of wet granular material. (c) 2021 Elsevier B.V. All rights reserved.