On October 13, JR Tokai held a ceremony to mark the opening of the first Minamikoma Tunnel of the Linear Central Shinkansen Line. In Yamanashi Prefecture, construction is underway on the west and east sides of the Linear Test Line, which has already undergone a series of test runs. The first Minamikoma Tunnel is the entrance to the mountains of the Southern Alps, passing through the Kofu Basin. In attendance were 160 people from JR Tokai, construction companies, and the local Fujikawa town government.
As disclosed on JR Tokai’s Web site, construction is underway in Yamanashi Prefecture on the “Southern Alps Tunnel (Yamanashi Prefecture side),” “Minamikoma Tunnel No. 4,” “Minamikoma Tunnel No. 1,” “Tonegawa Koenbu Viaduct,” “Kamanashi River Viaduct,” “Usui-Ahara Viaduct,” and “Fuefukigawa-Nigori-gawa Viaduct.
The total length of the line in Yamanashi Prefecture is 83.4 km (including the Yamanashi Linear Test Line 42.8 km), 27.1 km of which is aboveground and 56.3 km of which is in tunnels, and is currently mainly excavating tunnels and installing viaducts.
Excavation of the first Minamikoma Tunnel, which was opened to the public, began in March 2023 from the Shinagawa direction, and it took approximately one year and seven months to penetrate the tunnel. This is the first penetration of the main tunnel (the main tunnel where the train actually runs) between Shinagawa and Nagoya, except for the Linear Line Test Line.
The excavation of the Minamikoma Tunnel No. 1 was approximately 710 m long, and was carried out using the New Austrian Tunnelling Method (NATM), which is considered the standard method for mountain tunnels. After excavation, concrete is sprayed around the tunnel and reinforced with rock bolts to ensure safety and efficiency. Once the tunnel was penetrated, a tarp was installed to finish the tunnel, and concrete lining and roadbed concrete were used to solidify the tunnel to completion. On the way to the ceremony site, a drill jumbo used for excavation, a heavy-duty dump truck for transporting earth and sand, and a concrete spraying machine for hardening the walls with concrete were on display.
As soon as the ceremony began, the penetration work to drill the hole was conducted. The breaker was applied to the front face of the excavation, and the rock drilling began with a roar of “da-da-da-da! The rock drilling began with a roaring sound. As everyone watched the work, the hole was opened in about two minutes, and when the light shone through, they celebrated the penetration with applause and a hurray.
Mr. Takashi Watanabe, Director of the JR Tokai Chuo Shinkansen Yamanashi West Construction Office, took the podium as the representative of the operator. He explained that shortly after excavation began, they encountered a weak spot in the ground, but the joint venture and subcontractors’ reliable technology helped them overcome the difficulty and reach the present day. He said, “We will continue to work together with the operator and contractor, emphasizing construction safety, environmental preservation, and regional cooperation.
As the local representative, Toshiki Mochizuki, Mayor of the town of Fujikawa, took the podium to offer his congratulations. He said that the moment of penetration must have been a reward for the hard work of those involved, and added, “I can see the future beyond this light. I am truly thrilled as well,” he said. He also mentioned that this was the first penetration of the main shaft, and said that he was happy for the local government and hoped that the tunnel would be opened as soon as possible in the future in order to strengthen the national land. After the congratulatory speeches, a stone commemorating the tunnel penetration was presented by the contractor.
Mayor Mochizuki also explained in an interview that amulets made of stones from the tunnel penetration will be offered as a gift in return for tax payment. The stone collected at the tunnel penetration point is called “Nuki-seki,” and has been prized as a talisman for safe delivery, according to a legend that Empress Jingu “won a great victory in battle by attacking from a cave dug behind the enemy and brought back the stone from the cave as a souvenir, which enabled her to safely give birth to a healthy baby. Tunnel construction is still a difficult undertaking even today, and the stone is said to symbolize “overcoming difficulties” and “fulfilling one’s first desire,” and has recently become popular as a good luck charm for success in entrance examinations.
After the ceremony, we were able to take pictures of the surrounding scenery from an observatory at the site. More than 80% of the Linear Chuo Shinkansen’s running section will be underground or in mountain tunnels, but the Kofu Basin has many elevated sections, so bridge and other construction work could be faintly seen in the distance.
© Source travel watch
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