Hydraulic Characterization of a Pervious Concrete for Deep Draining Trenches

Reduction of pore water pressures is a useful strategy to improve the stability of slopes. Deep draining trenches can be used for this scope. For the realisation of deep trenches, the usual conventional construction techniques are not adequate and the use of adjacent vertical panels, built by means of the methods well established for diaphragm walls, is necessary. However, unbonded materials (i.e. gravels) cannot be used, since the excavation of a panel adjacent to already built ones will cause instability. For this scope a bonded material such as the pervious concrete can be used. It must have high permeability, filtering capacity in order to prevent the internal erosion of the soil in which the trench drain is installed, sufficient shear strength after a short curing time avoiding the instability of adjacent previously built panels. This paper reports the hydraulic characterization of two mixtures of pervious concrete carried out in the laboratory. The hydraulic conductivity has been measured insaturated conditions. Then, the water retention functions of the mixtures have been experimentally deduced, by investigating different calculation options, and their impact on the simulation of seepage processes through an unsaturated soil mass, in which an ideal trench is located, has been studied.