Management Office of the South Main Canal of Beijing South-to-North Water Diversion: 3D printing soft plugs to prevent backflow of stagnant water during flood season

The flood season has come. Once it rains heavily, the valve wells of some water transmission tunnels are low-lying. In extreme cases, they may face the risk of flooding, threatening the safety of drinking water for citizens. Recently, the South Main Canal Management Office of Beijing’s South-to-North Water Transfer Project has specially developed 3D soft plugs. Inspectors can quickly complete the plugging operation before or in the rain to ensure the safety of water supply. Wang Yanqiang, head of the Engineering Section of the South Main Canal Management Office, introduced that after the first phase of the South-to-North Water Diversion Project is completed, it is mainly used for urban residents’ domestic water.

After entering Beijing, the water conveyance tunnel of the South-to-North Water Diversion Project was buried deep underground, continuously transporting the “water of life” to thousands of households. However, because most of the valve wells of the South Main Canal Project are located in the five-ring green belt, and the ground in some valve well areas is low-lying, water accumulation is prone to occur during the flood season, and extreme circumstances must be strictly prevented from inverting the valve well. “In the past, sandbags, geomembrane, and plastic sheets were mainly used to deal with the hidden dangers of inversion, but it was relatively time-consuming, laborious, costly, and the blocking effect was not guaranteed.” Wang Yanqiang said, in order to ensure 100% safety of the “water of life” In response to the potential hazard of flooding water inverted valve wells during the flood season, the staff of the Engineering Department conducted several on-site investigations, carried out technical analysis meetings and on-site experiments, studied solutions, and did practical work for the masses. After many researches and explorations, the engineering department tried to use the method of “rubber cushion + customized soft plug”, which can quickly seal the wellhead in emergency situations to prevent the accumulation of water from pouring into the interior of the well. There will be a gap between the manhole cover and the well circle. The engineers and technicians first installed semi-circular or trapezoidal standard rubber cushions specifically for the gap to reduce bumps and damage when the manhole cover is opened and closed, and reduce the probability of water entering the valve well.

Secondly, for manhole cover holes that are prone to leaking, technicians measure the shape and size on site according to the material, shape, size and wear of the hole, use computer modeling, 3D print custom molds, and then use AB silicone material to make personalized soft plugs . When temporary blocking is required, the inspectors bring custom-made soft plugs, which can quickly complete the blocking operation before or during inspections in the rain. Recently, the Nangan Canal Management Office will successively install sealing rubber rings on more than 100 wellheads along the project. According to the requirements of the “Southern Main Canal Management Office Flood Control Emergency Plan”, when an orange rainstorm warning is issued during the flood season, inspectors will use custom rubber soft plugs to quickly seal the holes in the manhole cover along the line, effectively reducing the accumulation of water into the interior of the well, ensuring the safety of the project. The water quality is safe to ensure the smoothness of the flood.