ABSTRACT
Intense pore water flow through a stable packed soil bed can lead to a liquefaction and hence to failure of structures like submarine slopes. While in geomechanics the soil is treated as a stable soil skeleton subjected to effective stresses, the liquefied soil has to be dealed with in a different manner. With the transition of the soil bed to a liquid state, it has to be treated as a viscous liquid with different properties compared to its stable condition. To gain a deeper understanding of the micromechanic actions taking place at the transition from a solid to a liquid state and vice versa, a multiscale approach, namely a combination of the Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM), is used. In the coupled CFD-DEM, the soil particles are tracked in a Lagrangian way at a microscale level. The fluid phase, e.g. the pore water, is modelled as a continuum in CFD, solving the pore water flow with the Reynolds averaged Navier-Stokes equations. In a first step, the saturated soil of the seabed will be disturbed by a pressurized flow leading to liquefaction. The second step consists of the sedimentation of the soil grains. These investigations will help to draw conclusions about the void ratio and the stress state in the soil during liquid-solid transition.
