Breach Discharge Estimates and Surface Velocity Measurements for an Earth Dam Failure Process Due to Overtopping Based on the LS-PIV Method

Measuring the surface velocity and breach outflow discharge is a challenge in earth dam-break experiments. To solve this problem, large-scale particle image velocimetry (LS-PIV), a non-intrusive approach to measuring surface velocities, was applied in earth dam-break experiments. In this paper, two dam-break experiments were conducted in a large flume, and LS-PIV was used to measure the surface flow velocities of the dam breach. The flume was 50 m long, 4 m wide and 2 m high, and an idealized, non-cohesive, homogeneous earthen dam was placed in the middle of the flume. Three pressure sensors were used to measure the water depth over time. In addition, three high-speed digital cameras and two industrial cameras were used to record the dam breach process. The measured velocities were applied to evaluate the breach outflow discharge. Acceptable agreement was obtained between the discharges estimated with the LS-PIV and water level change methods. The surface velocity field was also obtained, and a dam crest cross section was selected to analyze the process of surface velocity change. Moreover, a convenient and simple formula was introduced to rapidly estimate breach discharge at the dam crest cross section. Finally, based on the Manning formula and surface velocity, the shear stress of the breach bottom was computed and discussed. The findings of this paper validate the accuracy and reliability of the LS-PIV technique for dam-break experiments and suggest that it is a reliable and advantageous technology for dam failure experiments.