Prediction of rainfall-induced transient water pressure head behind a retaining wall using a high-resolution finite element model

Retaining walls are used to provide additional support to slopes thought to be at risk of failure. The design of such structures requires the inclusion of pore water head in the appropriate calculations, whilst subsequent construction can have major implications for the overall slope pore water head regime. Despite the obvious importance of pore water head in this context there has been no rigorous model development facilitating the temporal as well as the spatial high-resolution computation of pore water head. This paper reports on the development of a soil water finite element model (ESTEL-2D), which is capable of achieving this. The model is applied to a typical Hong Kong retaining wall scenario where the model is shown to be capable not only of establishing ‘dynamic steady state initial conditions’, but also of illustrating the complexities of the pore water head changes occurring immediately adjacent to a retaining wall. The results suggest that it is entirely appropriate to consider the utilisation of such modelling capability to assess drainage requirements (including optimal drainage locations) and appropriate piezometric monitoring strategies.