Abstract
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.
Highlights
Retaining structures play a crucial role in the construction of different infrastructure facilities, such as roads, railways and underground urban transportation systems
In order to take into account the principal features of the mechanical response of coarse-grained soils under cyclic and dynamic loading conditions, e.g. non-linearity, irreversibility, dependence on pressure and density, stress- and stress historydependent dilatancy, the hypoplastic constitutive model proposed by von Wolffersdorff has been adopted in this work [4]
The results of the parametric study carried out in this work show the dramatic impact that excess pore pressure generation might have on the seismic performance of flexible retaining structures in sands
Summary
Retaining structures play a crucial role in the construction of different infrastructure facilities, such as roads, railways and underground urban transportation systems. Instability or failure of such structures under seismic conditions has caused severe technical and economic problems in the past, often due to the accumulation of permanent displacements at the end of the earthquake This is the reason why, in the past few years, retaining structures of various kind have attracted significant attention within the scientific community, leading to both experimental and theoretical research activities, focused on the behaviour of both rigid, gravity-type walls and flexible diaphragms and sheetpiles. For the former kind of structures, the current design criteria, based on the conventional (force-based) pseudo-static approach or, more recently, on the (displacement-based) Newmark’s method, typically allow a satisfactory assessment of the wall response under seismic loading conditions [1]. A number of nonlinear, fully coupled FE simulations of an ideal, but realistic, retaining structure subjected to an earthquake have been carried out in parametric form, as detailed
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