Hydraulic performance of tetrapod barriers in rivers

This paper refers to an experimental study to ascertain the hydraulic behavior of an innovative use of the artificial armor units called ‘TETRAPODS’, widely used in coastal engineering, for river or creek barriers as an alternative to massive concrete or rubble mound (rock) structures. The experimental study has been carried out in a laboratory flume using small scale tetrapods (specific weight: 235 kN/m3) in order to give preliminary guidelines for the use of this technology. The experimental procedure and the results are reported in the paper. Several barrier configurations and dimensions have been tested up to and beyond the collapse limit under different hydraulic conditions. The dimensional analysis determined that the relationship between the tetrapods dimensions, the barrier configuration, the discharge and the hydraulic stability can be described in terms of a proper non-dimensional surge h* and a non-dimensional specific discharge q*. A unique formula, h* versus q*, with various coefficient depending on the bed slope, is able to describe the hydraulic effect of all the tested structures while the stability threshold can be expressed by a limiting value q*.