Acoustic Scanning of Damaged Pipelines in Soil

The dynamics of a pulsed signal propagating in an underground pipeline with a damaged section is investigated. Pressure waves propagating in a linear pipeline filled with a fluid are considered. Due to viscous friction and thermal conductivity, dissipation is taken into account in a thin liquid or gas layer near the wall. It is assumed that the damaged pipeline section is a reflecting surface. Conditions on this surfaces are obtained under the assumption that the rate of liquid leakage during wave propagation through the damaged section is determined by the permeability of the soil. It is shown that in weakly permeable soils, signals do not provide full information on damage, and in well-permeable soils, only short (high-frequency) pulsed signals can be used to detect damage.