Abstract
The piping flow erosion process, involving the enlargment of
a continuous tunnel between upstream and downstream, is a
major cause of water retaining structures. Such a pipe can be
imputed to roots or burrows. The coefficient of erosion must
be known in order to estimate the remaining time to failure
and to downstream flood. The Hole Erosion test is a
laboratory experiment especially suited to estimate a priori
this geotechnical parameter. We propose therefore simplified
expressions for the remaining time to breaching accounting
for this erosion parameter. We established that the radius
evolution of the pipe follows a two-parameters scaling law.
The first parameter is the critical stress. The second parameter
is the characteristic time of piping erosion, which is a
function of the initial hydraulic gradient and the coefficient of
erosion. We establish here new mechanically based relations
for water retaining structures. The time to failure and the 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 finally
inferred from 18 case studies