Modular precast concrete facing for soil-nailed retaining walls: laboratory study and in situ validation

Abstract

A new concept for constructing the facing of soil-nailed walls is proposed and validated through experimental and numerical approaches. This new process uses precast concrete panels. For each excavation step, the soil reinforcements are first connected to the panels. A slightly cemented 4–6-mm crushed stone is then injected, through the weep holes, between the panels and the excavation vertical cut, applying a confining pressure to the ground and providing continuous high-capacity drainage behind the facing. The structural design of the precast reinforced concrete panel, based on full-scale loading tests in the laboratory and nonlinear numerical simulations, is presented in detail. Crack initiation and failure modes are properly predicted by the model. A full-scale experimental soil-nailed wall 7.5 m high was also built to evaluate the environmental, economic and mechanical performances of the new construction technique compared to the conventional shotcrete technique. The new construction technique greatly improves worker’s safety, significantly reduces construction duration and cost and improves the mechanical behaviour of the soil-nailing technique and drainage of the facing. Compared to the conventional shotcrete technique, the new technique reduces concrete consumption by 64% and greenhouse gases emission by 56%.