Abstract
Continuum numerical modeling of dynamic crack propagation has been a great challenge over the past decade. This is particularly the case for anticracks in porous materials, as reported in sedimentary rocks, deep earthquakes, landslides, and snow avalanches, as material inter-penetration further complicates the problem. Here, on the basis of a new elastoplasticity model for porous cohesive materials and a large strain hybrid Eulerian–Lagrangian numerical method, we accurately reproduced the onset and propagation dynamics of anticracks observed in snow fracture experiments. The key ingredient consists of a modified strain-softening plastic flow rule that captures the complexity of porous materials under mixed-mode loading accounting for the interplay between cohesion loss and volumetric collapse. Our unified model represents a significant step forward as it simulates solid-fluid phase transitions in geomaterials which is of paramount importance to mitigate and forecast gravitational hazards.
Highlights
Continuum numerical modeling of dynamic crack propagation has been a great challenge over the past decade
Anticrack propagation is believed to be at the origin of dangerous dry snow slab avalanches[10] that are responsible for most avalanche accidents
Existing models based on critical state soil mechanics (CSM) fail in reproducing the postpeak strain-softening behavior of porous cohesive materials since only hardening is allowed in compression
Summary
Continuum numerical modeling of dynamic crack propagation has been a great challenge over the past decade. Once the initial failure reaches a critical size, the fracture propagates along the slope possibly leading to the detachment and sliding of the overlying slab if the slope-parallel gravitational force overcomes friction[12] While such avalanches were for a long time believed to initiate due to mode II shear fracture[13], recent experiments reporting fracture propagation on flat terrain as well as observations of remote avalanche triggering[14,15] challenged classical theories. This contradiction highlighted the crucial role of the cohesion loss and volumetric collapse of the porous structure of the weak layer which is generally accompanied by a so-called “whumpf” sound, indicator of snowpack instability. We show that our unified model simulates both the release and flow of slab avalanches at the slope scale
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