A Two-Stage, Self-Pressure-Controlled Smart Manhole System with Motor-Driven and Lifting Mechanisms for Enhanced Flood Disaster Preparedness

Frequent extreme rainfall events by climate change have substantially heightened drainage system loads, often resulting in manhole cover dislodgment, property damage, and injuries from open manholes. To address this escalating risk, this study proposes a self-pressure-controlled smart manhole system comprising a motor-driven rotating blade for initial pressure regulation and a lid-lifting mechanism for secondary relief under high-intensity flows. By offering two distinct opening stages, the design successfully mitigates excessive internal pressures and velocities that would otherwise endanger public safety. Through computational fluid dynamics (CFD) simulations and verification using a 3D-printed prototype, the system demonstrated the capacity to reduce internal pressures by up to 99.5% and lower peak flow velocities by approximately 93.4% compared to conventional closed-cover conditions. These results underscore the effectiveness of the multi-phase approach in managing both moderate and severe inflow scenarios, providing a viable strategy for improving urban drainage resilience against increasingly frequent and intense rainfall events.