著者

黒田 泰介

出版者

日本建築学会

雑誌

日本建築学会計画系論文集 (ISSN:13404210)

巻号頁・発行日

vol.84, no.766, pp.2629-2638, 2019 (Released:2019-12-30)

参考文献数

13

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This paper aims to clarify the architectural characteristics of the Third howitzer platform in the remains of the Chiyogasaki Battery, the Tokyo Bay Fortress based on the results of the measurement survey using the three-dimensional laser scanning. The Chiyogasaki Battery (completed in 1895) is a Coastal Battery in the Meiji era set up against the invasion of enemy ships to Uraga Channel, the entrance of the Tokyo Bay and to support the southern side of the Kannonzaki Battery, the core of the Tokyo Bay Fortress. The Chiyogasaki Battery was composed of three platforms: Howitzer platform for the sea front defense, Cannon and Mortar platform for the land front defense of Kurihama beach. After the Second World War the abandon battery was transformed into a pig farm. Thereafter the site was purchased by Japan-Self Defense Force and it was reused as the Naval transmission station (1960-2010). The platforms were filled up but JSDF reclaimed the second gun platform at the time of withdrawal (2013). The Chiyogasaki battery was designated as the National Historic Site in 2015 and Yokosuka city, the site administrator unearthed the Third gun platform (2018). At that moment there was no academic research on the Third howitzer platform and the author’s survey became the first one. The Chiyogasaki Battery remains the original design and structure: the retaining walls built of cut Tuff stones (Bosyu-ishi) using an Bluff bond, the brick wall in English bond, the use of clinker bricks for open-air part and the barrel vaults in concrete. These are valuable examples of the progress of the modern fortification in Japan and also these have the important values in the history of Japanese architecture and civil engineering. In this paper, I clarified the historical background and the outline of the Tokyo Bay Fortress and the Chiyogasaki battery. Then I verified the feature of the Third howitzer platform referring the precise drawings and the cross section perspectives made from the Point cloud of 3D scan data. These drawings clearly visualize the total composition of the underground structure of the Chiyogasaki Battery. With these drawings I verified the architectural characteristics such as the plan of the third platform, the configuration of the two howitzer emplacements, shell rooms on the retaining wall built in Bluff bond and the connection with the upper corridor and the munitions depot for the Third howitzer platform. The cross section perspectives also explains the shell transportation system of the shells at the Third howitzer platform through two lift holes and the carriage rails on both side of upper corridor. Especially I examined the unearthed structure of the second gun emplacement: the round pit (diameter 5.89m) on the concrete slab and the octagon basement made of the cut Andesite blocks. I superimposed the plan of the base plate of howitzer on the basement and I found the deviation (208mm) between the center of the howitzer’s basement and the round pit. The deviation and the size of the round pit allow the gun the very limited rotatable range (83.24°, Azimuth 151.51° - 234.75°) to the direction sight. Showing the firing range of the 28 cm howitzer on the second gun emplacement, I clarified the firing system of the Third howitzer platform and I considered the role of the howitzer platforms for sea front shooting.