PRESSURE PROPAGATION AND LOCALIZATION OF PORE WATER FLOW DUE TO SAND VOLCANO - PIPING HOLE FORMATIONS IN RIVER LEVEES

Abstract

 In recent years, there has been increased risk of piping failure due to water leakage and sand volcano in the levee due to the infiltration of river water into the permeable foundation ground. Elucidation of the piping mechanism of river levees and examination of important monitoring points are important issues in the future. In this paper, three-dimensional saturated-unsaturated flow analysis and experiments were carried out focusing on the generation of sand volcano and piping hole formation under the levee for the piping mechanism. As a result, the state of the propagation of the decrease in water pressure in the foundation ground due to the generation of sand volcano was reproduced by analysis. In addition, as the piping hole develops, at the tip of piping hole, the flow velocity increases due to three-dimensional water collection from the range of about 10 times the diameter of piping hole, and in particular in the case of multiple layers, seepage acts on the entire piping hole . It became clear that it becomes a factor to promote.