CHARACTERIZATION OF SOIL ATTENUATION FOR ACOUSTIC CONDITION ASSESSMENT OF WATER-FILLED METAL PIPES

摘要

Acoustic-based technologies provide economic and non-disruptive means of actively monitoring water networks, accurately detecting leaks, and efficiently assessing the condition of buried pipelines. They rely on interpreting the propagation of sound waves in a buried pipeline, which is a function of the properties of the fluid, conveying pipe, and surrounding medium. Currently, there are no non-invasive methods of measuring tuberculation of iron pipes. Tubercula-tion is an accumulation of corrosion products on the inside of water mains which can result in reduced pressure in water distribution systems and increases in the potential for leaks. This research addresses the attenuation of sound waves in metallic pipes in an attempt to predict the degree of tuberculation. At present, we are unable to distinguish between the attenuation associated with the inside surface of the pipe (tuberculation) and the attenuation caused by the surrounding medium (usually soil). This project involved both modeling and experimental phases. First, influencing parameters from the soil were identified and incorporated into a wave attenuation model. Then, this model was tested and validated in a realistic setting. Field tests were conducted on a 100 m long pressurized iron pipe in order to compare and analyze the attenuation characteristics of exposed and buried pipes. The results from attenuation measurements for different configurations showed good agreement with the attenuation predictions from the model of soil-pipe interactions (less than 3% difference). With this better understanding of how the soil affects acoustic wave propagation, the attenuation associated with the inside surface of the pipe can be isolated and used to estimate the degree of tuberculation. Such an interpretation technique will allow water utilities to better understand their water networks, empowering them to better manage our precious water resources and infrastructure.