Influence of Pier Geometry and Debris Characteristics on Wood Debris Accumulations at Bridge Piers

Abstract

This paper analyzes the influence of the geometry of bridge piers and supplied debris on the formation and growth of wood debris jams at bridge piers. A total of 162 laboratory experiments were conducted. Experimental results showed that the maximum size of debris jams formed by the accumulation of cylindrical debris (i.e., wooden dowels) is smaller than that of jams formed by natural nonbranched wood of irregular shape. In addition, experiments with branched debris resulted in jams that were significantly smaller and less stable than those with nonbranched natural debris. Finally, comparison of experiments conducted with six different pier shapes indicated that the shape of the pier has negligible effects on the maximum size of a woody debris jam. The only exception to this observation was for square piers, which showed slightly larger debris jam sizes than the other types of piers tested.