DL E&C is moving to target the market by leveraging its technology specialized in pumped storage. A pumped-storage power plant consists of upper and lower dams that impound water, a vertical tunnel connecting them, and an underground power station that generates electricity using water from the dams. Among these, DL E&C is standing out in the "underground power station process" and the "vertical tunnel process."
DL E&C said on the 3rd that it has developed, patented, and is pushing to commercialize a "pumped-storage specialized slipform (a mold that shapes poured concrete)" method that can efficiently construct ultra-deep vertical tunnels more than 100 meters underground. As orders for pumped-storage power plants are increasing with the expansion of renewable energy, the company aims to strengthen its construction capabilities to support this.
The core of this patent lies in improving how the slipform moves inside the tunnel. Previously, hydraulic jacks were used to push the slipform upward. In contrast, this technology suspends the slipform from a wire so it is installed as if floating in midair. Based on the slipform, the workers' movement lines are separated into upper and lower sections so the work area is not confined to the lower space. As a result, tasks that were previously carried out sequentially in the upper and lower spaces can now be performed simultaneously. This increases work efficiency and safety while also shortening the work period by 20% compared with the conventional method.
Given the nature of pumped storage, which generates electricity by dropping water from the upper dam to the lower dam, the height of the vertical tunnel reaches several hundred meters. Considering that a vertical tunnel for the GTX (Great Train eXpress) is usually around 50 meters, the conventional method has limits. As such, the RBM (Raise Boring Machine), a state-of-the-art excavation device, is considered essential. It is a large machine that drills through bedrock by rotating a head equipped with dozens of cutters and requires highly sophisticated control technology. Over the past five years, DL E&C has been the only domestic builder with RBM construction experience.
Using an RBM, DL E&C recently completed tunneling that vertically penetrates Busan's Yokmang Mountain. It bored through a peak equivalent to a 43-story apartment building to create a 120-meter vertical tunnel. The RBM method is also set to be applied as a core technology at the Yeongdong pumped-storage power plant now under construction.
The underground power station at a pumped-storage plant is a key process that determines the overall construction period and has a scale and characteristics similar to a deep-underground subway station. DL E&C proved its competitiveness by successfully completing, with its technology, construction of Seoul Station on the GTX-A line, the largest underground space in Korea.
Park Sang-shin, CEO of DL E&C, said, "Based on our specialized technology for the vertical tunnel process and our experience executing special underground space projects such as Seoul Station on the GTX-A line, the largest urban underground space in the country, we will be able to secure a competitive edge in the pumped-storage market going forward," adding, "By advancing these technologies and experiences, we will speed up our push into the pumped-storage market, including the Pocheon pumped-storage power plant now out for bid."