Gwangmyeong underground tunnel 'pillar damage' occurred... Construction company says "No risk of collapse"

The collapse accident that occurred at the Gyeonggi Gwangmyeong Sinansan Line underground tunnel construction site on the 11th was found to have shown signs of collapse, such as pillar damage, starting 17 hours prior.

On the 13th, Congressman Moon Jin-seok of the National Assembly's Land, Infrastructure, and Transport Committee (Democratic Party) reported that according to the initial situation report received from the Ministry of Land, Infrastructure and Transport, the construction company POSCO E&C confirmed that the tunnel pillar was damaged at 9:50 PM on the 10th, the day before the accident, and evacuated the workers underground. This was 17 hours before the collapse.

Looking at the photos attached to the report, the concrete pillars supporting the tunnel arch are cracked in several places. Beneath the pillars, broken rebar and concrete debris are piled up. The report also states 'central tunnel pillar damage.'

However, the construction company only informed Gwangmyeong City around midnight, two hours later, that "cracks had appeared in the pillar," and it is said that they also told the police who arrived at the scene around the same time that "there probably isn't a risk of collapse."

The police official said, "We plan to verify whether the construction company reported the situation inaccurately."

The construction company, around 4 a.m. on the 11th, conducted a safety inspection with the Korea Tunnel and Underground Space Society, and began reinforcement work by adding an 'H-beam' next to the pillar around 7 a.m. Later, at approximately 3:13 p.m., the construction site collapsed, trapping two workers working on the ground.

Professor Choi Myung-ki of the Korea Industrial Field Faculty Corps, who reviewed the initial situation report, said, "If the pillar was damaged this severely, there would have been signs such as visible cracks at least a week prior," and added, "It seems that safety management was neglected."

The construction company also described the reinforcement work method as "seems to have underestimated the situation." Professor Park Chang-geun of the Department of Civil Engineering at Catholic Kwandong University said, "Instead of welding H-beams onto already damaged columns, support steel supports like jack supports should have been inserted first to ensure safety before proceeding with reinforcement work." The 12 workers who were underground at the time of the accident evacuated immediately when the ground collapsed, but the two buried workers, who were working on the surface, were unable to assess the situation in time. Experts stated, "This is also evidence that the construction company did not seriously consider the risk of collapse."

The site where the collapse accident occurred is also pointed out by the Board of Audit and Inspection as having weak ground. In the January 2023 'Audit Report on the Status of the Construction of the Metropolitan Transportation Network,' the Board of Audit and Inspection stated, "In the case of the 5th Construction Section of the Shinan-San Line (Siheung City Hall to Gwangmyeong), the ground is in very poor condition, with rock fragments falling off in a section about 19 km from the tunnel point," and pointed out that "even so, the 'Invert' was not reflected in the tunnel design." The invert is a concrete structure used to reinforce weak ground.

Regarding this, the construction company stated, "We reflected the invert in the design in accordance with the audit office’s opinion at the time."

 

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POSCO E&C is the construction company. Before something bigger happens.

It seems we need to conduct a thorough re-inspection overall.. All the construction managers should properly take responsibility..

Before a bigger accident happens...