2023 Volume 18 Issue 2 Pages 223-238
Small displacements of Shinkansen viaducts can be fatal for running safety. Therefore, not only ultimate bearing capacity but settlement is an important verification index of the foundation structures. The plain area at Omura city in Nagasaki prefecture, located between Takeo-onsen and Nagasaki station of the Kyushu Shinkansen, is composed of unusual soil, that is sandy gravel with coble stone, and the Shinkansen viaducts have not been constructed on such type of the soil. In addition, the soil in Omura was not simply considered as a bearing stratum for the shallow foundations because N-values from the standard penetration test varied widely, and the minimum was 20. However, shallow foundations have a cost advantage over other foundation types like pile foundations. Therefore, the authors examined the application of shallow foundations in this site with the in-situ test, self-boring typed in-situ friction tests, plate loading tests, and triaxial tests using the specimens sampled by gel push method. As a result, the design values of the soil were suggested, and the performance required for shallow foundations was verified with the proper management method.
