Study of the Dilatancy/Contraction Mechanism of Landslide Fluidization Behavior Using an Initially Saturated Granular Column Collapse Simulation

Abstract

Debris flows and landslides are the most frequently occurring geological disasters in mountainous environments (F. C. Dai, et al., 2002;Dowling & Santi, 2014). The solid phase of debris flows and landslides is typically composed of granular materials (Iverson, 1997;Lajeunesse et al., 2005). According to their definitions, debris flows and landslides have considerably different motion behaviors. Debris flows exhibit fluidlike continuous shear deformation, whereas landslide deformation is localized along a shear zone or slip surface (Iverson et al., 1997). However, the motion state of landslides may partially or completely evolve to a state similar to that of the debris flow (Iverson et al., 2015;Yin et al., 2016) under certain conditions because of the complete or partial liquidation of the water-laden solid phase (Iverson & George, 2016). This phenomenon of the motion state transformation driven by the pore fluid pressure can be termed fluidization transformation. The fluidization transformation of landslides leads to the expansion of the effect area and increase in the motion speed. It is necessary to study the transformation mechanism to predict the motion process of landslides and debris flows.To understand the physical processes of unsteady granular flows, dry, immersed, and wet granular column collapse experiments and simulations have been conducted. The dry granular column collapse experiments highlighted that the flow phenomenon, kinematic process and deposition profile are highly dependent on the initial aspect ratio a = H i /L i (Lajeunesse et al., 2005;Lube et al., 2004Lube et al., , 2005 and internal friction angle (Balmforth & Kerswell, 2005), where H i and L i denote the initial height and length of a granular column, respectively. In experimental scenarios, the effect of the ambient fluid can be neglected during the dry granular column collapse process for large granules. However, Roche et al. (2008Roche et al. ( , 2011 experimentally demonstrated that the pore gas pressure that was initially imposed by a vertical air flux through the granular

Micro computed tomography images of capillary actions in rough and irregular granular materials

“…Capillary actions are known to strongly influence the strength and flow properties of granular materials 1 – 4 , thus playing a fundamental role in several natural and engineering applications (e.g. slope stability 5 , earth construction 6 , building foundations 7 , caking in pharmaceutics 8 and agriculture 9 to name a few). These actions rise at the interfacial equilibrium (i.e.…”

River-Blocking Risk Analysis of the Bageduzhai Landslide Based on Static–Dynamic Simulation

“…The flume was described by the dynamic boundary conditions. The specific numerical implementation process can be found in the following research papers [25][26][27][28].…”

“…Li et al used the SPH method to evaluate the critical slip surface derived by the limit equilibrium method [24]. Liang introduced boundary repulsion to improve the boundary conditions used in the framework of the SPH method and simulated the dynamic process of landslides in the construction of solid waste landfills and the impact of debris flows on bridge piers [25][26][27][28]. Zhao T et al used the coupling method of the discrete element and computational fluid dynamics (DEM-CFD) to simulate the formation process of landslide dams in narrow rivers [29].…”