Piping flow erosion in water retaining structures

The piping flow erosion process is a major cause of the degradation of water retaining structures. The erosion coefficient must be known to estimate the remaining time to failure and downstream flooding. The hole erosion test is particularly well adapted for estimating this geotechnical parameter. Simplified expressions are proposed in this paper for the remaining time to breaching by accounting for this erosion parameter. New mechanically based relationships are established for water retaining structures. The time to failure and peak flow are related to the two basic parameters of piping failure: the coefficient of erosion and the maximum pipe diameter prior to roof collapse and breaching. Orders of magnitude of the coefficient of erosion and the erosion rate are inferred from 18 case studies.