Effects of Large-Space Latticed Walls for Liquefaction Mitigation

The 2011 East Japan earthquake induced widespread liquefaction not only in the Tokyo bay area but also in the inland area of the Kanto region, which damaged numerous residential houses and public buildings. A research project was conducted to develop large-space latticed soil-cement mixed walls and vertical drains and their combination, which can be installed as measures to mitigate liquefaction of grounds of existed residential houses and buildings. This paper reports the results of dynamic three-dimensional effective stress analyses for reproducing the dynamic centrifugal tests. The results show that the latticed walls can prevent lateral deformation of liquefiable layer. At the same time, the vertical drains not only ensure that a high level of excess pore water pressure won’t be generated in liquefiable layer within the latticed walls during earthquake, accordingly maintain the foundation strength of liquefiable layer, but also prevent seepage drainage from the outsides of the latticed walls into the liquefiable layer. Parametric studies were carried out to investigate the effects of the spacing of latticed soil-cement mixed walls and vertical drains on the liquefaction mitigation. The results show that the larger the spacing of the latticed walls and the smaller the effects of liquefaction mitigation, however, even the spacing of the latticed walls expanded, they still can limit in a certain extent the lateral deformation of liquefiable layer. Numerical analysis was also carried out to evaluate the effects of liquefaction mitigation for the liquefiable ground of a three-story office buildings.