In many countries, leaks are located in water distribution pipes by using the cross-correlation of pipe vibration measured either side of a suspected leak. However, in modern plastic pipes this can be problematic due to strong coupling between the water, the pipe and the soil, affecting the propagation of leak noise within the pipe. This paper concerns an analytical, numerical and experimental investigation into the way in which soil properties influence leak noise propagation in buried plastic water pipes. The analytical model allows a detailed investigation into the physical effects of the soil on leak noise (wave) propagation in the pipe, in particular on the wave speed and wave attenuation. Results highlight that, in addition to the pipe hoop stiffness, the shear stiffness of the soil can have a significant effect on the wave speed in the pipe. Experimental measurements were conducted at two different sites-one in the UK and the other in Brazil. In the UK system, both dilatational and shear waves in the soil propagate away from the pipe, resulting in large wave attenuation in the pipe. However, in the Brazil system, only shear waves propagate resulting in smaller wave attenuation in the pipe.
Acoustic correlators have been used for many years to locate and detect leaks in buried water distribution pipes. Currently, the only way to compare different correlators directly is in the field. This can be problematic as it may be difficult to present exactly the same conditions to each correlator. In recent years, the way in which leak noise propagates in buried water pipes has been determined, and this has enabled the development of a virtual pipe whose behaviour can be simulated in the computer. By coupling the filtering properties of the pipe with electrodynamic shakers, a proof-of-concept virtual pipe test-rig has been developed that will allow different correlators to be compared directly in laboratory conditions. Different situations, such as pipe material and size, and measurement positions, as well as leak strength can be simulated. The theoretical basis of the test-rig and details of the proof-of-concept system are discussed in this paper. It is shown that careful consideration of the dynamics of the shakers is vital if the system is to faithfully model situations that are found in the field.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.