Half 2D model tests on seepage failure of soil in front of sheet piles were carried out. Seepage failure tests on H2D and original 2D soils are discussed. Based on the results, it is clarified that there is no scale effect for the original 2D and H2D test results, and non-dimensional formulization for the critical hydraulic head difference against seepage failure, Hc, is possible. The hydraulic head differences at the onset of deformation, Hy, for the half model soil, original test soil, and real soil must be plotted at the same point on the non-dimensional relationship, when they are geometrically similar. Non-dimensional formulization and the reproducibility of the relationship between hydraulic head difference H and discharge Q are also discussed.
During the excavation of soil with a high ground water level within a cofferdam, seepage water flows through soil under a hydraulic head difference, H, between up- and downstream sides of a sheet pile wall. The seepage failure of soil is often a problem in front of sheet piles. Half 2D test apparatus, or a half model of the original 2D test apparatus, was designed for examining and comparing with each seepage-failure test result. To clarify the two-dimensional seepage failure mechanism, experiments on H2D soils in front of sheet piles were conducted for various cases, and analyses of FEM seepage flow and stability against seepage failure of soil using the prismatic failure concept (pfc) were carried out. Theoretical critical hydraulic head differences based on pfc are defined as Hc. The non-dimensional formulization and reproducibility of the H – Q relationship are first discussed based on the 2D and H2D test results, where Q is the discharge. Whether or not the non-dimensional formulization for the critical hydraulic head difference against seepage failure, Hc, is possible, is also discussed from an experimental point of view.
