Effects of strong ground motion duration on the liquefaction behavior of a river levee

Abstract:

In the Chubu region, central Japan, two kinds of earthquakes are likely to occur with different duration characteristics: ① the Tonankai-Tokai coupled earthquake, with duration longer than 100s at a maximum acceleration of about 2.4 m/s2; ② an inland earthquakes due to active faults, with duration shorter than 20s at a maximum acceleration of about 6.0 m/s2. Saturated loose sand deposits are widely distributed over the low alluvial plain in this region and therefore have a high liquefaction potential..Based on the Biot theory for simulating coupled hydro-dynamic behavior in saturated porous media, this study presents a numerical assessment of the seismic behavior of a river levee founded on liquefiable foundation soils under earthquake loading. Analysis is carried out using an effective stress-based, fully coupled, finite element method, in which the behavior of the liquefiable sand is described by means of a cyclic elastoplastic constitutive model. The liquefaction responses of the river levee are compared for two different earthquakes. From the numerical results, it is found that the strong motion duration has a significant effect on the liquefaction behavior of the levee including excess pore water pressures, accelerations, and deformations. The longer ground motion may lead to much larger settlement of the river levee.