World's largest hybrid TBM debuts in Changsha

The world's largest earth pressure balance (EPB) double shield hybrid tunnel boring machine, or TBM, was officially rolled off the production line for the first time in Changsha, Hunan province, on Wednesday.

The TBM is called Qiangji, which means Strong Foundation. China Railway Construction Heavy Industry Corp and China Railway 18th Bureau Group Corp jointly developed the 12.68-meter-diameter tunneling behemoth, which will help construction of a 12.28-kilometer drainage tunnel in Hangzhou, Zhejiang province.

Qiangji integrates EPB technology for soft-soil stability and double shield capabilities for hard-rock excavation. It is specifically engineered to conquer the tunnel's complex geological challenges.

The breakthrough marks China's leading technological advancement in ultra-large-diameter tunnel boring equipment, injecting new momentum into urban flood control and underground space development.

Weighing 3,500 metric tons and stretching 107 meters long, the TBM also features cutting-edge digital integration. Its intelligent assisted tunneling system and automatic segment handling system allow operators to monitor over 20 real-time parameters – including cutter head rotation speed and propulsion rate – via a smart interface.

Supported by an automated guidance system, the equipment achieves millimeter-level precision in tunneling. Additionally, digital twin technology enables visualized, full-process construction control.

The TBM will be deployed to China's largest deep-tunnel drainage system in terms of flood discharge capacity, tunnel diameter and burial depth. The project will alleviate flood risks in the Taihu Lake Basin, enhance flood resilience for western Hangzhou and establish an urban safety barrier for the city's main districts.