Hydraulic characterization of a pervious concrete for deep draining trenches

Reduction in pore water pressure is an useful strategy to improve the stability of slopes. Deep draining trenches can be used for this purpose. For the realization 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, because the excavation of a panel adjacent to one already built will cause instability. For this scope a bonded material such as pervious concrete can be used. It must have high permeability; filtering capacity, in order to prevent internal erosion of the soil in which the trench drain is installed; and sufficient shear strength after a short curing time to avoid the instability of adjacent previously built panels. This paper reports the hydraulic characterization of two mixtures of pervious concrete carried out in the laboratory. Hydraulic conductivity was measured in saturated conditions. Then, the water retention functions of the mixtures were 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.