Abstract: The construction of traffic and ventilation tunnels in pumped storage power stations often presents challenges for conventional tunnel boring machines(TBMs) due to their large excavation sections, small horizontal turning radii, as well as large and frequently changing longitudinal slope gradients. Therefore, a case study is conducted on the Funing pumpedstorage power station to analyze the focal points and difficulties of TBM construction in traffic and ventilation tunnels with large diameters, ultrasmall turning radii, and large slopes. A TBM designed with an ultrasmall turning radius, suitable for large excavation sections and slopes, is designed considering the overall selection scheme, key component design, and innovative slag transportation methods. The study concludes that: (1) The designed TBM is feasible for constructing traffic and ventilation tunnels with a large diameter, an ultrasmall turning radius, and a large slope. It offers environmentally friendly, green, lowcarbon, and highly efficient technology. (2) The doubleshield main body combined with boltshotcrete support can adapt to large diameters and ultrasmall turning radii. (3) The integration of a steel bar storage and discharge system onto the support shield of the doubleshield TBM is feasible. (4) The mucking system of the "rotating stack platform and rubbertire selfdumping truck" can address the challenges of TBM slag and material transportation under conditions of large longitudinal slopes and continuous ultrasmall turning radii, and the construction cost and failure rate are relatively low. However, it affects TBM tunneling speed and hinders material transportation and personnel passage during mucking, resulting in an uncivilized construction phenomenon. (5) The combined belt conveyor system is favorable for slag transportation under continuous ultrasmall turning radii and large slope conditions, considerably improving TBM excavation speed. However, the belt deviation adjustment technology and "multilevel control and sequential start and stop" control system need to be further investigated.

Key words: largediameter tunnel boring machine; large slope, ultrasmall turning radius, pumped storage power station, mucking and transportation, combined belt conveyor