The results of an experimental study carried out in 1993 of the use of riprap to protect bridge piers against scour are presented. Experiments involved several sizes of bed sediment and riprap, and different types of bridge piers, under conditions involving general sediment transport and bed lowering. The interaction between adjacent piers and between a pier and an adjacent abutment is considered.
A theoretical basis for the design of the riprap, considering stability against entrainment into the flow, embedment into the underlying sediment, and compatibility of filter layer with riprap layer, and of riprap with bed sediment is developed. A complete design procedure, and an example, for the design of riprap pier scour protection systems is appended.
Keywords: bridges, bridge scour, hydraulic design, scour protection, riprap, roads