Design and Application of a Shaft-Type Water Level Observation Platform Based on the Diversion Tunnel

To reduce the construction difficulty of water level observation platforms for large dams and reservoirs, and to provide stable and favorable observation conditions, the upstream chamber of the diversion tunnel closure structure is utilized as a water connectivity device, forming a shaft-type water level observation platform. The key to this structure is ensuring the reliable sealing mechanism of the inlet pipe during the rise in water levels, in order to guarantee the successful blocking of the diverted tunnel and effective water connectivity. Finite element simulation and engineering case studies have proven that the new shaft-type water level observation platform can achieve a sealing effect under designed water pressure, with the impact of installation accuracy on the sealing effect being minimal. After the sealing measures are released, the water level in the observation shaft changes synchronously with the reservoir water level, achieving the expected results. Where topography and geological conditions permit, the new shaft-type water level observation platform makes comprehensive use of diversion structures, not only eliminating water surface fluctuations and reducing sedimentation but also providing excellent water level monitoring conditions. At the same time, it reduces the cost and construction difficulty of hydrological facilities, shortening the construction period.