Numerical modeling and experimental evaluation of a time domain UWB technique for soil void detection

A growing percentage of waste and storm water conveyance systems are approaching or exceeded their design life, suffering from accelerated deterioration and subsequently increased rates of failure. Discontinuities in the pipe wall may lead to the formation of voids in the soil embedment surrounding it via the transportation of fine soil particles by infiltrating ground water. This paper describes a method that utilizes ultra wideband (UWB) time domain principles to detect the presence and location of soil voids in early stages of formation, thus preventing a catastrophic collapse of the pipe and/or a structure above it (e.g., road surface). A three dimensional numerical model simulating the propagation of UWB pulses within a buried pipeline was developed. The results from the numerical model were validated using experimental measurements performed utilizing a full scale test bed. It is shown that a UWB based sensory system is capable of detecting even minor voids around non-ferrous buried pipes.