Influence of Wind Velocity on Measurement of Concrete Surface Roughness Using Aerial Ultrasonic Sensor

Abstract

The hydraulic performance of irrigation and drainage canals is relied on roughness of concrete surface. The aerial ultrasonic sensor is effective tool of measuring the roughness of concrete surface. In this paper, we focused on the influence of wind velocity when using the aerial ultrasonic sensor. We measured the peak to peak of the reflected wave by a wind tunnel experiment. Consideration was given to the influence of wind velocity on the peak to peak, as well as the influence of wind on the estimate of arithmetical mean roughness, and the theoretical value and measured value were compared. As a result, the followings became clear. As the wind velocity increased, the peak to peak decreased. When we set the wind velocity as 10 m/s, the decreasing rate from peak to peak of wind velocity as 0 m/s was: smooth board (Ra: 0.04 mm): 4.4%, rough board (Ra: 0.32 mm): 7.2%, and rough board (Ra: 1.04 mm): 11.1%. As a result of estimating of the arithmetical mean roughness of each wind velocity, the following became clear. When we set the wind velocity as 4 m/s, the influence of wind velocity was small. When we set the wind velocity as 8 m/s, the estimate of arithmetical mean roughness increased by about 0.1 mm compared with the estimate of arithmetical mean roughness at 0 m/s. When we set the smooth board, the theoretical value and measured value were in relatively good agreement. When we set the rough board, the peak to peak distance was decreased below the theoretical rate due to the influence of the scattered wave.