Last August, a sinkhole accident occurred in the middle of Yeonhui-dong, Seodaemun-gu, where a passenger car driving fell into the sinkhole, causing serious injuries to two passengers. In September, a similar incident happened in Busan, where two trucks fell into a sinkhole, highlighting the increasing frequency of such accidents recently.
Sinkholes often occur due to cracks and damage in old sewage pipes. According to the Korea Land and Geospatial Informatix Corporation, 4.2 out of 10 sinkhole accidents are caused by this reason. Leakage from sewage pipes erodes the surrounding soil, creating empty spaces that lead to the formation of sinkholes.
To address this issue, the Korea Institute of Civil Engineering and Building Technology announced on the 6th that it has developed a trenchless method for the repair and rehabilitation of deteriorated sewage pipes, known as the “Trenchless Rehabilitation Method for Flexible Sewage Pipes.”
The repair method was developed as a reinforcement technology that minimizes lifting and reduces the cross-sectional area of existing pipes when inserting a liner (a rehabilitated pipe created by curing a tube impregnated with thermosetting resin on-site).
This method increases the elasticity of the reinforcing material by at least 20% by attaching acrylic fibers to existing glass fiber reinforcements.
Furthermore, it reduces the thickness of the reinforcing liner by up to 50% while allowing it to respond to pipe deformation. The driving part of the construction equipment is designed with a five-link structure to always position it at the center of the deformed pipe.
By doing so, the adhesion and durability of the liner are enhanced. The research team emphasized that this method allows stable construction without lifting issues, even in severely deformed pipes.
Additionally, the team derived an optimal laminated structure to maximize the integral movement effect between reinforcements, resulting in a liner’s bending modulus that is more than eight times higher than before.
Compared to existing methods (CIPP, a method of structurally reinforcing existing pipes by curing thermosetting resin on-site), this reduces the liner thickness by half, minimizing the reduction in pipe capacity and contributing to alleviating flood damage during heavy rains.
Park Sun-kyu, the president of the research institute, stated, “The flexible pipe reinforcement lining method is designed to effectively rehabilitate deteriorated flexible pipes. This method is expected to play a crucial role in preventing the rapidly increasing sinkhole accidents, thereby protecting public safety.”
Meanwhile, this research project, “Development and Demonstration of High-Strength Light-Curing Trenchless Partial Repair Method for Sewer Pipe Deformation,” was carried out with the support of the Ministry of Science and ICT.