Experimental Investigation of Loading due to Debris Dams on Structures

Abstract

The entrainment of debris in tsunami-induced floods and storm surges can result in their accumulation on structures, a phenomenon known as debris damming. Such dams can decrease the stability of the affected structures by increasing the area of the flow obstruction, resulting in increased resistance forces. The formation of debris dams can also result in upstream water level rise. This study investigated the influence of idealized debris dam geometry on induced loads and changes in the free surface surrounding a circular column in steady-state flow conditions. Additionally, it investigated the resistance force coefficient of the debris dams. Results show that the presence of debris dams results in a significant increase of loading on structures. The increase in the resistance force was up to 7.7 times greater than the resistance force acting on the column with no debris present. The resistance force coefficients and the change in water depth were functions of the relative dam height and the Froude number, while the porosity had an insignificant impact on the effective resistance force coefficients.