Abstract:
Headcut erosion is a major failure mode of homogeneous earth dam due to overtopping failure, and the velocities of the headcut migration have an internal connection with the physico-mechanical indexes. However, current foreign models studying the headcut migration rarely consider this connection, and may yield a relatively large calculation error. In this paper, based on a model for the headcut migration velocities utilizing the energy dissipation principle, meanwhile, considering the clay ratio, water content, and dry density of the dam materials, the measured water channel model test results of the headcut migration velocities have been chosen to fit the formula of the headcut migration parameters. Owing to the large variation of the dam materials, the upper and lower envelopes of the parameters are also put forward in the study. 7 large scale model tests carried out by USDA-ARS which have the measured headcut migration velocity data are chosen as the representatives to testify the rationality of the suggested parameters. The typical foreign models for the headcut migration parameters are chosen as well to calculate the headcut migration velocities. Through analytical comparison,the advantage of the suggested model is presented, and the reference range of the parameters is given. In order to analyze the impacts of clay ratio, water content and dry density on the rule of the headcut migration, the sensitivity analyses of 3 indexes are carried out. Those model test results can provide the approaches for determining the headcut migration parameters of the homogeneous earth dams, and give a reference for further studies on the mechanism of anti-erosion capability of the headcut.