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The East Japan Expressway (NEXCO East Japan) said a new underground cavity was found near the site of the road collapse that occurred in a residential area on the Tokyo Outer Ring Road (Tokyo Highway) tunnel construction route. Tokyo Outer Ring Road) in the city of Chofu, Tokyo. It was announced on the 22nd. NEXCO East Japan said, “The causal relationship between the construction and the cavity is unknown at this time,” and began preparing to fill the cavity while continuing to investigate the cause. A cavity is found near the site of the cavity. sinking.
It was second place.
◆ Cavity length 27 m, width 3 m, internal height 4 m
The cavity was found on a city highway south of the depression site on October 18 during a boring inspection on the 21st. It was confirmed that a cavity 27 meters long, 3 meters wide and 4 meters wide was opened. internal height at a depth of 4 meters from north to south. Above the cavity, there are three houses across the road from the city. On the 3rd of this month, a cavity about 30 meters long was found in a vacant lot about 40 meters north of the sinking site.
◆ The shielding machine with the largest diameter of 16 m in Japan passes
About 47 meters underground, where the cavity was found this time, Japan’s largest shield machine with a diameter of 16 meters passed between September 11 and 12. Continuous vibrations and noise were generated from the basement, leading to damage such as cracks in the surrounding residential areas and detachment of the exterior wall tiles.
The investigation of the cause by NEXCO East Japan is scheduled until mid-December, but the location where the cavity was found this time was not found by the investigation of the cavity by the radar scanning vehicle. The radar reaches about 2 meters from the ground surface. It is necessary to significantly increase the number of boring inspection points, which can prolong the survey period.
◆ The single-family house with a garden you wanted …
“I can’t live here anymore.” A man in his 50s, living in a residential area of Higashi Tsutsujigaoka, Chofu City, Tokyo, found a huge cavity 4 meters below his house and looked up at the sky.
From the night of 21-22, I was angry at the person in charge of NEXCO East Japan who came to explain in turn, saying, “It is not possible to make a hole in our basement and fill it this time. Explain the construction method and the construction period correctly “. .. In the future, you plan to pursue compensation negotiations, including the purchase of your home.
17 years ago, he looked for a quiet environment and said, “I want a house with a garden.” I liked the lush green setting near Tsutsujigaoka Station on the Keio Line.
It was in mid-September that I became aware of the “incident.” “Gashern”. I heard the sound of the exterior wall of the house in front of me across the street from the city peeling off and falling onto the street. From the basement, I was concerned about the daily vibration and noise, and the block wall of my house was damaged by cracks. And this time the cavity. Of the total length of 27 meters, more than 10 meters drilled my house site from north to south.
“I believed that Japan’s civil engineering technology is the best in the world and that underground tunnel construction can be safely traversed” (Katsunori Hanai)