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The lower half of the Tsushima mine entrance appears - International Highway Foundation July issue

◆The side wall of the lower half of the Tsushima Aren Shaft entrance construction is revealed!



It has been decided that the construction of the entrance to the Aren Shaft in Tsushima will be constructed using the liner plate method, and work is progressing smoothly. The liner plate method is a construction method in which the lower half is made of reinforced concrete, and the upper half is made by assembling H steel into an arch shape and hardening it with concrete. Once completed, the entrance to the tunnel will be 6m in diameter, 5.2m long, and 1m lower after 4m.


In early June, the construction method and location for the tunnel entrance were finalized, and construction began immediately. It was determined that the best way to install the tunnel would be to build it about 2 meters in front of the tunnel slope and backfill the surrounding area with soil to blend in with the mountain. The tip of the excavator is equipped with a rock-crushing device called a ``breaker,'' and it is driven into a huge layer of hard rock, making it smaller. The crushed earth and sand are transported by dump trucks to widen the ground at the mine entrance. ``As you can imagine, the rock layer is hard, so it took a long time,'' said the site supervisor.



Although it is the rainy season, there is little rain and the work is proceeding smoothly. Starting on June 14, the floor surface was prepared at a one-quarter downward slope, concrete was poured, reinforcing bars were erected, and the formwork into which concrete was poured was erected over two days. The height is 3m. On the 20th, ready-mixed concrete was poured into the formwork of the left and right side walls. Currently waiting for the concrete to dry.



The formwork was removed on June 30th, revealing the lower half of the mine entrance. After backfilling and soil improvement work to soften the soil, the upper half of the tunnel will be delivered in mid-July, and if all goes well, the tunnel entrance will be completed by the end of the year.

The Tsushima Arirang Festival, one of Tsushima's summer festivals, was held on the first Saturday and Sunday of August, but was canceled last year due to the Buddhist statue issue, but it will be resumed this year. The hot festival season is coming to Tsushima.


International Highway Foundation Newsletter July 2014 issue (PDF viewing/download)

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