The spiral ramp at the Beishan laboratory features complex working conditions, including a maximum slope of 10%, a minimum horizontal turning radius of 255 m, and seven consecutive 90° turns in the same direction. To overcome the technical challenges of mucking when using a tunnel boring machine to bore large-slope variable-grade spiral tunnels, a systematic study of a continuous-belt conveyor is presented and integrates theoretical analysis, numerical calculation, factory tests, and engineering verification. First, three mucking methods are compared in terms of turning radius, longitudinal slope adaptability, safety, and economy, verifying the suitability of continuous-belt conveyors for mucking in spiral tunnels. Focusing on the force characteristics of conveyor-belt units in turning sections, the turning mechanism of conveyor belts is established based on the formula for the minimum turning radius derived from mechanical equilibrium. In addition, the adjustable parameters and feasible measures for improving the turning radius of continuous-belt conveyors in spiral tunnels are explored. Furthermore, based on the structural design configuration and operational methods of continuous-belt conveyors, the layout parameters, such as distributed drive, dual storage belt chambers, idler trough angle, adjustable hanging chains, and forward-inclined idler installation, are optimized, augmented by research into technical measures, including idler densification, automatic deviation correction, and intelligent monitoring. Finally, factory tests are conducted to verify the turning radius of continuous-belt conveyors. The research results lead to the following conclusions: (1) Continuous-belt conveyors are suitable for mucking in spiral tunnels, with attention to turning. (2) The key factors for conveyor-belt turning are trough angle, inner curve elevation angle, and tension. (3) Parameters such as distributed drive, dual storage belt chambers, idler trough angle, adjustable hanging chains, and forward-inclined idler installation are optimized, enabling continuous mucking by belt conveyors under largeslope and continuous small-radius turning conditions. (4) Stable operation in factory tests and at construction sites verifies the reliability of the continuous-belt conveyor system.