Evaluation of the effect for a liquefaction countermeasure using enlarged spacing of the lattice shaped ground improvement method by centrifuge model test and its FE analysis

摘要

In order to evaluate the effect of the effect for a liquefaction countermeasure using enlarged spacing of the lattice shaped ground improvement method, three cases of centrifugal model tests were carried out. The first one was without countermeasure and the other two cases were with countermeasure of 10 m depth and 8 m depth respectively. Toyoura sand was used for liquefaction layer. The model ground was prepared with 60% relative density by air pluviation method. The model for stabilized bodies were made by mixing sand and cement then cured one week before installing in the ground. The model ground was saturated by silicon oil. The centrifuge model tests were conducted in 60 g of centrifugal acceleration and the depth of potential liquefaction layer was 10 m. Three levels (100 gal, 250 gal, 400 gal) of earthquake motion were applied to the model. As the result, both of two countermeasure cases were effective in controlling the ground deformation and excess pore pressure despite of enlarged spacing of the lattice compared to conventional design. In addition, dynamic effective stress analysis FEM was applied to simulate the test results. Comparison between experiment and analysis results is discussed in the paper.