Was the collapse predicted? Three years ago, the Board of Audit and Inspection found that the ground was ”extremely poor” - South Korean media

The Board of Audit and Inspection has issued an audit finding stating that the ground in the construction area, which includes the site of the underground tunnel collapse accident in Gwangmyeong, Gyeonggi Province, three years ago, is "extremely poor."
According to the "Audit Report on the Promotion of Wide-area Transportation Network Construction" released by the Board of Audit and Inspection in January 2023, the Board of Audit and Inspection had been investigating the establishment of plans for the wide-area transportation network, the progress of construction projects, and post-management.
In order to check whether the above was done properly, data collection and audits were conducted from September 2021 to December of the same year. The audit report states, "In the case of the 5th section of the Shinansan Line,
In a section about 19 km away from the tunnel, there is a fault zone with rocks broken and the ground condition is rated as Grade 5, which corresponds to a "very poor" condition.
"The installation of the invert has not been incorporated," it said. The invert is a concrete structure that is close to a circle. The Japan Railway Corporation, when building an underground tunnel in the city center section, requires the classification of the ground.
If the grade is 4 or below and is deemed "poor" or "very poor," an invert is installed at the bottom of the tunnel to accommodate ground upheaval.
The Board of Audit pointed out that despite the Korea Railroad Corporation's regulations, the design of the 5th section tunnel did not include the installation of an invert.
A researcher at a construction company said, "It's possible that this accident occurred because the ground was weak to begin with or because the ground became weaker due to a waterworks rupture or other reasons."
Two collapses occurred at the construction site of the Gurye Tunnel, which runs through Geumsan County, Chungcheongnam-do, in November 2012 and July 2014.
In the case of the collapse accident, the first accident occurred because the tunnel could not withstand the load of the soil. The second accident required additional ground investigation and reinforcement design after the first accident,
The accident occurred because this process was omitted. As a result of this accident, one of the excavator operators was left stranded underground, and one of the workers is currently missing.