Bi-layer diaphragm walls: Experimental and numerical structural analysis

The bi-layer diaphragm wall, a new type of wall, consists of two concrete layers, the first of which is poured and the second sprayed, in different construction stages. A major aim of the research conducted is to maximize the functional attributes of the second layer, enhancing both structural performance and watertightness. The central objective of this study is to corroborate the structural behaviour of these walls in experimental and numerical terms. It follows a three-step methodology: a full-scale experimental campaign; development of a Finite Element Model (FEM) capable of predicting the structural behaviour of the wall; and, assessment of the second layer contribution. The experimental campaign confirmed the viability of the constructive solution and the FEM model accurately reflected the experimental data. A comparison between the bi-layer wall and other single-layer walls showed that the contribution of the second layer permitted reductions in first-layer reinforcement, adding to its various other functional advantages.