Remediation of liquefaction effects for an embankment using soil-cement walls: Centrifuge and numerical modeling

Numerical simulations of a centrifuge model test of an embankment on a liquefiable foundation layer treated with soil-cement walls are presented. The centrifuge model was tested on a 9-m radius centrifuge and corresponded to a 28 m tall embankment underlain by a 9 m thick saturated loose sand layer. Soil-cement walls were constructed through the loose sand layer over a 30 m long section near the toe of the embankment and covered with a 7.5 m tall berm. The model was shaken with a scaled earthquake motion having peak horizontal base accelerations of 0.05 g, 0.26 g, and 0.54 g in the first, second, and third events, respectively. The latter two shaking events caused liquefaction in the loose sand layer. Crack detectors embedded in the soil-cement walls showed that they developed only minor cracks in the second shaking event, but sheared through their full length in the last shaking event. The results of the centrifuge model test and two-dimensional nonlinear dynamic simulations are compared for the two stronger shaking events using procedures common in engineering practice. The effects of various input parameters and approximations on simulation results are examined. Capabilities and limitations in the two-dimensional simulations of soil-cement wall reinforcement systems, with both liquefaction and soil-cement cracking effects, are discussed. Implications for practice are discussed.