Investigation of Flow Characteristics of Landslide Materials Through Pore Space Topology and Complex Network Analysis

Abstract

AbstractUnlike embankments, earth dams, and other man‐made structures, most landslide dams are formed by rapid accumulation of rock or debris rather than mechanical compaction; thus, they are loose and pose a great risk of seepage failure. Landslide materials usually have complex pore structures with randomly distributed pores of various sizes, making the flow and transport processes very complex. Aiming at these challenges, we systematically investigated the influences of pore structure on the micro‐and macro‐scale flow characteristics of landslide materials. First, landslide materials are simplified as spherical granular packings with wide grain size distributions. Then, we use the Finite‐difference method Stokes solver to simulate the fluid flow through granular packings and calculate their permeability. We characterize the pore structure using different topological measures, including these borrowed from complex network theory. Among these measures, tortuosity and global efficiency show clear relations with permeability. The pore network modeling indicates that pore size heterogeneity and pore connectivity significantly influence the flow characteristics. The correlation between pore‐scale velocity and throat diameters follows a power‐law scaling with an exponent close to two, suggesting that the Hagen–Poiseuille law would still be valid in complex porous media. The permeability and porosity, throat radius, and tortuosity of pore structure can be related by the equation proposed by Nishiyama and Yokoyama (2017, https://doi.org/10.1002/2016JB013793). The complex network analysis reveals that the assortative network is more permeable than the disassortative network. Furthermore, pores with larger closeness centrality have higher flow efficiency, resulting in higher macroscopic permeability.