Countermeasures for earthquakes and liquefaction are now made at ports and airports, so it is essential to make existing facilities earthquake-resistant. As a construction method to prevent liquefaction of ground directly under existing facilities and ground surrounding buried structures, the density increasing method and the chemical grouting method are frequently used. Generally, when the ground of the original location is heterogeneous and when the fine content is relatively high, construction tends to be challenging. But if construction is performed forcibly, problem such as localized deformation at the surrounded ground will be developed. Therefore, in this study, the improvement effects on heterogeneous ground by the chemical grouting and the densification method are investigated.

In this study, visualization technique such as a transparent soil was employed to visualize ground deformation. As the transparent soil, we used crushed transparent quartz particles and refractive index matching solution to make the model ground transparent. In centrifuge model tests, we simulated grout injection and investigated the effects of different ground conditions on the improved area.

This new visualization method is practical, and can visualize complex intraground penetration and deformation behavior, both of which have been challenging previously. Going forward, we will conduct numerical simulations and other strategies regarding phenomena observed in experiments and will use the results to develop a method to predict ground improvement effects. Also, this experiment method is expected to be applied to various geotechnical engineering problems other than ground improvement.