A joint research group of Ube Kosan, Port and Airport Research Institute, Japan Agency for Marine-Earth Science and Technology, Tokyo Institute of Technology, and Tokyo Institute of Technology has established a method for continuously measuring the pressure and strain generated inside a hardened body on the deep sea floor, and is the first in the world. Data measurement was started by installing a cement hardened body and measuring equipment on the actual deep sea floor.
The area of the deep sea occupying the exclusive economic zone of Japan, which is a maritime nation, is very large, and various possibilities such as energy use in the deep sea, installation of structures utilizing the seabed, and the concept of a deep sea city are being investigated.
However, it has been reported that the hardened cement, which is supposed to be used as a construction material for marine infrastructure, has deteriorated significantly in the deep sea, and basic data on how the extreme environment in the deep sea affects structures using cement. Needed to be collected and evaluated.
In the past, a submersible was used to measure changes in the hardened material after it was recovered from the deep sea. It was not possible to accurately evaluate the phenomenon that occurred in.Therefore, in this study, in order to analyze and consider the data by extracting only the phenomena occurring in the deep sea, we established a new method of "in-situ measurement" of the pressure and strain generated inside the cured body on the deep sea bottom.
In July 2020, the research group installed a hardened body and a measuring device in the sea area at a depth of about 7 m at the northern edge of the Nankai Trough located 70 km off Suruga Bay. It will be collected during FY3500 and the measurement results will be analyzed, which will clarify how the hardened cement will be deformed by the action of high water pressure in the deep sea for a short period and a long period of time. Be expected.In the future, it will be useful for the development of infrastructure materials in the deep sea and the construction of structural design methods.
