An ultrasonic prototype to remedy pipes clogging: experimental effects on drains used for landslide mitigation

Abstract

In many cases it is observed that drains or piezometers used in hydrogeology or landslide mitigation, often at considerable cost, may partly or wholly lose their function—even in few months—due to phenomena such as scaling, fouling, corrosion, etc. Several techniques are already available to overcome these problems, but none has proved decisive and/or effective in every situation. The use of ultrasonic technology in this context has certainly highlighted the complexity of the physical and chemical phenomena that characterize these kinds of problems. Analyzing the results obtained from tens of laboratory tests, it was noted that several factors play a role, and that such factors can somehow influence the effect of ultrasonic waves in removing fouling. However, it was highlighted that, for small diameter drainage (<10 cm in diameter) applications, using continuous or pulse frequencies of 25–20 kHz can give amazing results. The action of these mechanical waves results in the removal of impurities from solid surfaces. Any foreign object lodged or firmly anchored to the internal or external surface of the drain is broken down and crushed by ultrasonic waves. The forecasts for their useful application are optimistic: the working time was estimated, from laboratory tests, in the order of tens of seconds per meter so the time this technique should takes for the operation of cleaning in real cases would be almost 1–2 h for each drain, depending of course on the length, nature and severity of clogging.