Methods of reducing the erosion from cells in a concrete block spillway

摘要

In recent years concrete blocks with cells have been extensively used to provide auxiliary dam spillways or to protect other surfaces subjected to supercritical flow. When the cells are filled with topsoil and grass is allowed to grow, their use is currently limited by the Construction Industry Research and Information Association (CIRIA) guidelines to a maximum velocity of 8 m/s. In addition a geotextile underlayer is recommended to prevent damage to the embankment material when soil and grass is eroded from the cells in a flood. The mechanism of removal of granular material from a cell by flowing water is presented in this paper. Two simple modifications to the cell geometry are also described—a bar across the upper surface or a step in the downstream cell wall—which reduce the depth of erosion by at least 50%. Such modifications would limit the amount of maintenance necessary to the spillway after a flood and reduce the reliance upon the geotextile to prevent failure.