Yeosu Ungcheon Earth Retaining Wall Collapse Accident 'Cause Announcement' Full Effort to Prevent Recurrence

Administrative Actions Against Construction Companies and Supervisors for Poor Earth Retaining Wall Design and Construction

Strengthening Safety Measures Including Enhanced On-Site Inspections by External Experts

[Yeosu=Asia Economy Honam Reporting Headquarters Reporter Choi Cheol-hoon] Jeollanam-do Yeosu City (Mayor Jeong Gi-myeong) announced the cause and handling plan of the earth retaining wall collapse accident that occurred at the construction site of a new residential lodging facility in Ungcheon-dong, Yeosu City last November.

The city formed the ‘Yeosu City Underground Accident Investigation Committee’ and investigated the cause of the accident for about three months to identify the cause of the collapse and prepare measures to prevent recurrence.

Yeosu City Hall Exterior [Photo by Yeosu City]

According to the investigation committee, the site created by reclaiming the coast has a geographical characteristic where tidal differences occur due to seawater influence. During the underground excavation, waterproofing (preventing water leakage or inflow) should have been prioritized, but construction and management in this regard were found to be insufficient.

Originally, the design planned the earth retaining wall on the waterway embankment side to be made of waterproof SHEET PILE, but during the earth retaining wall construction, due to complaints such as noise, it was changed to C.I.P (Cast In Place Pile) walls with lower waterproof performance, and auxiliary waterproofing methods were not considered.

As a result, partial incomplete waterproofing occurred, leading to soil loss, formation of loosened areas, and increased earth pressure, which likely caused the collapse of the C.I.P wall.

Additionally, considering the special characteristics of the reclaimed land, thorough analysis during the earth retaining wall design and more rigorous quality control in wall construction and measurement management were required, but quality management was found to be insufficient.

Problems were also identified during the construction process, such as partial over-excavation and delays in STRUT (horizontal braces for earth retaining walls) installation during underground excavation.

Based on the investigation results, Yeosu City plans to take administrative actions against the construction company, supervisors, and related personnel.

Along with this, the city intends to make every effort to prevent recurrence based on the analysis of the cause of the earth retaining wall collapse.

First, the design for the earth retaining wall construction will be supplemented, and a ‘Small-scale Underground Safety Impact Assessment’ will be applied for to the Ministry of Land, Infrastructure and Transport, with the results reflected in the design documents.

A Yeosu City official stated, “We plan to approve the resumption of construction after securing the stability of the underground excavation through measures such as waterproof grouting in the temporary restoration section, establishing a drainage plan, and external expert site inspections at least once a week during excavation.” He added, “To prevent similar accidents, we will strengthen the review of earth retaining wall construction on coastal reclaimed land and involve related experts in construction safety inspections to enhance on-site inspections.”

Yeosu=Asia Economy Honam Reporting Headquarters Reporter Choi Cheol-hoon hss79@asiae.co.kr