Final steady state of sloping capillary barriers under constant intensity rain: development and numerical validation of a simplified method of analysis

A new simplified method of analysis is proposed for predicting the final steady state behaviour of sloping capillary barriers subjected to continuous rain of constant intensity. In contrast to an existing simplified method, the proposed new method assumes approximate final steady state suction profiles on vertical cross-sections of the finer layer that are appropriate for sloping capillary barriers, with flow parallel to the slope in the lower part of the finer layer. Numerical validation, performed by hydraulic FE modelling, shows that, in all cases studied, the final steady state profiles of suction, degree of saturation and horizontal seepage velocity predicted by the new simplified method are excellent matches to the corresponding results from FE simulations. As a consequence, values of water storage capacity and water transfer capacity are accurately predicted in all cases, together with the final steady state variation of water stored with horizontal coordinate. A parametric study shows the influence of key variables (slope angle, material of finer layer, thickness of finer layer and rainfall intensity) on water storage capacity and water transfer capacity of sloping capillary barriers.