From Scaled-Down to Full-Scale Rockfill Dams with Dry-Stone Pitching: A Numerical Study

Abstract

Rockfill dams with dry-stone pitching are about one hundred years old structures that are present in the French heritage. They are composed of a backfill made of decametric blocks and a protective pitching made of hand-placed stones without mortar on both dam's downstream and upstream faces. Electricity of France, a French stakeholder, operates approximately ten dams of this kind. However, the mechanical behavior of such a structure which is discrete in nature and that can bear large deformations is not very well understood, even if few studies have been conducted over the last decades. This study is a step forward for a better understanding of the role of the pitching in both static and seismic behaviors of such dams. Firstly, a mixed DEM-FEM numerical approach for the modeling of such dams is developed and validated based on experiments involving scaled-down rockfill dams. Secondly, simulations on full-scale dams are carried out and the role of the pitching considering different building techniques or properties is quantified. They clearly show large-scale effects at stake in the structure and the key role of the pitching weight and pitching-backfill interface. Finally, the perturbation in the dam resistance induced by a berm which is typically built on the downstream face is investigated.