Fully-coupled analysis for the behaviour of flexible retaining structures under seismic conditions

The study concerns the analysis of the behaviour of two propped reinforced-concrete diaphragm walls in coarse sand under seismic conditions. Fully-coupled dynamic equilibrium and pore water flow under unsaturated conditions for the soil have been taken into account, in order to assess the effects that the development of excess pore water pressures can have on the performance of such structures when dynamic conditions occur. The von Wolffersdorff hypoplastic model and the van Genuchten soil-water retention model have been used to describe the mechanical and retention behaviour of the sand. The Finite Element predictions of the soil and retaining structure behaviour show a significant dependence of the seismic performance of the structure - evaluated in terms of permanent displacements and structural loads, in view of the modern performance-based design criteria - on the excess pore pressures developed in the soil during the seismic shaking, even when dynamic liquefaction does not occur.