Floating Dry Process Caissons for Maintenance of Submerged Ocean Structures

摘要

According to trend on quality control of construction and maintenance, a development of semi-permanent method of construction is required for maintenance of submerged part of ocean structure, such as bridge, riser, jetty, pier, dolphins, etc. The present structures were being maintained incompletely, partly due to unskilled divers' work and limited working environmental conditions. Considering the easiness of access to the maintenance area and the cost for set up the working structure, especially for the case of structure slabs close to the sea surface and harrow pile span structures, we developed the floating type circular and sector dry process caissons (DPC), which are effective to the submerged ocean structures near the waterline by allowing dry working space. The DPC was appeared easy to move around the working area and handle. It also showed not only a significant reduction of maintenance expenses and time for anti-corrosion work but also better protection. Circular type caisson was fit for small steel or concrete piles but we propose a sector type for a large cylinder structures greater than diameter of 3m, instead of the full circular caisson. By doing this, it is easy to disconnect the caisson rapidly in emergence case. Therefore, we expect that the floating DPC will contribute to reduce working time and improve the quality of underwater work, and furthermore the use of DPC to other construction industry might be expanded in future days.