China’s TBM rescue beneath the Yangtze

During construction of the Jiangyin–Jingjiang Yangtze River Tunnel, a 6.4 km road tunnel beneath the Yangtze River, a 16 m diameter tunnel boring machine (TBM) suffered a catastrophic failure approximately 54 m below ground level. At that depth, the machine was subjected to high hydrostatic pressure and water-saturated soft sediments, making reversal, dismantling, or in-situ repair technically unfeasible. Abandoning the TBM would have resulted in a direct financial loss estimated at USD 50 million, alongside major schedule delays and potential cancellation of the project. Conventional contingency options offered little practical value under such constrained geotechnical and hydraulic conditions.

Faced with limited options, engineers pursued an unconventional solution: launching a second TBM from the opposite riverbank to intercept the disabled machine underground. This approach required exceptional control of alignment and ground behaviour beneath a major river. Predicting deformation, managing face stability, and maintaining trajectory over several kilometres demanded continuous monitoring and high-precision guidance systems. The operation culminated in a mid-tunnel docking with a vertical alignment error of just 2 mm and negligible horizontal deviation, achieved under high water pressure and weak ground conditions. Such accuracy is rarely attained in long-distance tunnelling and represents one of the most demanding operations in underground construction.

The successful docking enabled safe access to the failed TBM and allowed the tunnel drive to continue, effectively salvaging the project. Beyond the immediate recovery, the operation demonstrated that deep underground rescue beneath rivers is technically viable. It highlights the maturity of modern TBM guidance, ground prediction, and risk management systems, particularly in challenging geotechnical environments. Lessons from this intervention are directly applicable to future sub-river, sub-sea, and fault-crossing tunnels, where equipment failure has traditionally been considered terminal.