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TBM triumphs over one of the most difficult tunnels ever encountered
An 8 m (26.2 ft) diameter Main Beam TBM broke through at China’s Yin Han Ji Wei project in the first quarter of 2022.
The project is considered to be one of the most challenging ever completed by a TBM, with crews encountering abrasive hard rock up to 309 MPa (45,000 psi) UCS, over 14,000 rock bursts, and multiple severe water inflow events.
Crews overcame the challenges by utilizing the McNally crown support system, using Extra Heavy Duty (XHD) 20-inch disc cutters, increasing pumping capacity, and more.
With TBM tunneling complete, the route will become part of two other sections of an altogether 82 km (51 mi) long tunnel that will link up the Hanjiang and Weihe Rivers in Shaanxi province.