Surface and Subsurface Flow through Block Ramps

Block ramps are permeable hydraulic structures. Flow that enters the block ramp infiltrates between the blocks and eventually on the porous base material on which the ramp is posed. The percentage rate of subsurface flow with respect to the total flow at the entrance of a block ramp or a rock chute is studied experimentally and analyzed by means of dimensional analysis. This quantity is described as a function of related parameters, such as the total inflow discharge, the particles' characteristics, the thickness of the base material bed, the geometric characteristics of the block ramp, and the boundary conditions at the toe of the ramp itself. The experimental data were elaborated in order to supply new formulations of the flow discharge through the base ramp material and the block ramp energy dissipation. The amount of energy losses of such structures is essentially a function of the geometry and the bed surface characteristics of the ramp, the hydraulic conditions, and the percentage rate of the subsurface flow.