Structures of the Subgrade of the Old Nagasaki Highway and Abutment of the East Gate Bridge of Saga Castle

摘要

The Mietsu Naval Dock (MND) is a Dutch Western-style naval base constructed in 1858 by the Saga clan at the Hayatsue River, 6 km north of the Ariake Sea in Japan. The MND was constructed with large-scale revetments and a complex assemblage of planks and logs on the soft Ariake clayey layer. However, this type of structure cannot currently be found in Japan. In this paper, to investigate a structure of similar period on soft Ariake clayey layer to understand the wooden structure of the MND, the structures of the subgrade of the old Nagasaki Highway and the abutment of the East Gate bridge of Saga Castle were examined using an unconfined compression test and cone and hardness penetration tests in the excavated trench.