PREDICTION METHOD OF LEAKAGE AND SAND BOILING BASED ON THE LEVEE FOUNDATION VULNERABILITY INDEX t_b^*, AND SOIL CHRACTERISTICS AT THE TOE OF LANDSIDE LEVEE

Abstract

 This paper classified the levee foundation leakages in the Chikuma River and the Kakehashi River using the levee foundation vulnerability index t_b^* and soil characteristics of the toe of landside levee. We found: 1) underground leakages occur when 0.3 ≤ t_b^* ≤ 1.4; 2) sand boilings occur when t_b^* ≥ 1.4; 3) boilings and sliding failures following a sand boiling occur depending on the thickness and grain size of the levee foundation soil layer at the toe of landside levee; and 4) a leakage causing from the regional underground water in the alluvial fan and tributaries and a leakage seen frequently during floods occur when t_b^* < 0.3.