Granular / Multiphase Flow Observed in Civil Engineering Fields

(with an Emphasis on Solid/Fluid Phase Transition)

Abstract

The present article overviews some granular/multiphase flows observed in civil engineering fields and discusses their grain-scale mechanics. In particular, solid/fluid phase transition behaviors are highlighted to characterize the mechanics of granular materials. In liquefaction phenomena, uni-directional shear causes solidification of the system, while cyclic shear leads to liquefaction. This behavior can be understood as an induced anisotropy of granular packing structure. In rapid flows, kinetic stress increases with increasing shear rate, which may result in drastic reduction of shear resistance of the flow. Emphasis is also put on the significance of the analysis of long-term geological formation whose micro-mechanism is governed by the grain/fluid interaction during erosion, transformation and sedimentation process.