Chinese engineers made a million-dollar mistake, but the failure has become one of the most complex operations in history. It all started when a tunnel boring machine (TBM) became trapped under the Yangtze River.
China was building the Jiangyin-Jingjiang tunnel, a enormous infrastructure that stretched for 6.4 km under the Yangtze River. The construction could only be completed with a 16 meter wide tunnel boring machine.
A tunnel boring machine trapped 54 meters under water
The tunnel boring machine (TBM) is a huge machine that allows excavating the ground while supports the topsoil as it advances to engage the liner. This tool is common on roads that cross mountains or mega constructions such as the English Channel, also known as the Channel Tunnel.
Work on the section of the Yangtze River that would cross the Jiangyin-Jingjiang tunnel was progressing as planned until the tunnel boring machine failed. The breakdown left the tunnel boring machine trapped about 54 meters underground with a huge mass of water above her.
The machine had to sustain all the water pressure from above, although it ran a huge risk of collapsing. This would affect all the excavation achieved to date in the original section of the tunnel.
China does not back down on its plans
The Asian giant had two options: cancel the project with million-dollar losses or make a new investment to recover the tunnel boring machine. The second option was beginning to gain more and more strength.
The TBM could not be reversed, repaired in situ, or safely dismantled for recovery without affecting the infrastructure or the river ecosystem itself. This machine It obstructed the tunnel, so it had to be removed or the entire Jiangyin-Jingjiang route had to be redesigned. to avoid blocking.
The project was increasingly complex and delays could be years, although A third option emerged: rescue the tunnel boring machine with another tunnel boring machine. China’s idea was to use the same machine from the opposite bank of the river and direct it towards its stranded twin.
Chinese engineers had to predict the movement of the terrain under a rushing river and control the direction with millimeter precision. Landslides and continuous flooding were another huge problem.
The margin of error in rescuing the trapped TBM and joining the two parts of the Jiangyin-Jingjiang was less than the thickness of a coin. The engineers achieved it with a vertical error of only 2 millimeters.
This engineering feat allowed the stranded TBM to be towed underground. The second machine was coupled to its twin in the middle of the tunnel in one of the most complex operations of underground civil engineering.