Spiral Hard-Rock TBM Access Tunnel

CRCHI engineered a bespoke large-gradient spiral hard-rock TBM for a deep access tunnel project. The 7-metre diameter machine completed a 7.1-kilometre spiral incline, descending on a sustained -10% gradient through granodiorite of Class I to II integrity with uniaxial compressive strength peaking at 260 MPa. Negotiating seven 255-metre radius horizontal curves under fully unmanned excavation, the TBM held attitude deviations within 50 millimetres before breakthrough.