Abstract
Seepage failure is one of the most important problems associated with performance-based design of soil in high groundwater sites. Here, we discussed the movement of soil particles with increases in the up-and downstream hydraulic head difference H, during seepage failure experiments of soil within double-sheet piles, using PIV (Particle Image Velocimetry) analysis. The following conclusions were obtained:
(1) PIV analyses show movement of sand particles and boundaries between regions where soil particles do move or not.
(2) When H increases beyond Hd (≅Hy), downstream rise and upstream drop of the soil surface occur. PIV analyses show that soil particles move upward near sheet pile walls and upward toward the center of double sheet piles far from the walls. Hd and Hy are hydraulic head differences at an abrupt change in H≅Q15 curve and at deformation of soil, respectively.
(3) The movement of soil particles is limited to approximately the depth D and width D/2, which proves the validity of Terzaghi's method and the Prismatic failure concept, where D is the penetration depth of sheet piles.
(4) The relationship of HPIV≅Hd≅Hy is obtained, where Hpiv is the hydraulic head difference at the start of soil particle movement using PIV analysis.
