3D Finite Element Modelling of Hydraulic Efficiency of Drainage Trenches

In this work the hydraulic efficiency of a parallel draining trenches system is evaluated by performing a series of pseudo-3D consolidation analyses using the finite element method. A parametric study has been conducted to investigate the influence of relevant aspects of the problem such as the slope inclination and trench length, which are not considered in currently available 2D solutions. Starting from a case study as a reference, an ideal slope has been considered, in silty, saturated soil. The evolution in space and time of the pore-water pressure and hydraulic head has been evaluated and, consequently, the evolution of the average hydraulic efficiency of the drainage system has been assessed, starting from the construction phase to the final steady-state conditions. The temporal evolution of the hydraulic efficiency has been assessed as a function of the trench inclination, depth, length and interspacing. Results have showed that the trench inclination and depth have a limited effect on the average value of the hydraulic efficiency, whereas the trench interspacing and length (the latter accountable only with a 3D model) have a remarkable effect on it.