Simulation of Soils Under Rapid Cyclic Loading Conditions

The stability of structures strongly relies upon the strength and stiffness of the foundation soil underneath. If fluid-saturated or nearly saturated soils are subjected to rapid cyclic loading conditions, for instance, during earthquakes, the intergranular frictional forces might be dramatically reduced. Subsequently, the load-bearing capacity decreases or even vanishes, if the soil grains loose contact to each other. This phenomena is often referred to as soil liquefaction. Drawing our attention to fluid-saturated granular materials with heterogeneous microstructures, the modelling is carried out within a continuum-mechanical framework by exploiting the macroscopic Theory of Porous Media (TPM) together with thermodynamically consistent constitutive equations. In this regard, the present contribution proceeds from a fully saturated soil, composed of an elasto-plastic solid skeleton and a materially incompressible pore fluid. The governing material parameters of the solid skeleton have been identified for the research-unit sand. The underlying equations are used to simulate soils under rapid cyclic loading conditions. In this regard, the semi-infinite domain is split into a near field, which usually the domain of interest, and a far field, which extents the simulated domain towards infinity. In order to avoid wave reflections at the near-field boundaries an energy-absorbing layer is introduced. Finally, several simulations are carried out. Firstly, a parametric study of the particular far-field treatment is performed and, secondly, soil liquefaction is simulated, where the underlying initial-boundary-value problem is inspired by practically relevant scenarios.