Development of acoustic sensor and signal processing technique.

Abstract

Sewer flooding incidents in the UK are being increasingly associated with the presence of blockages. Blockages are difficult to deal with as although there are locations where they are more likely to occur, they do occur intermittently. In order to manage sewer blockage pro-actively sewer managers need to be able to identify the location of blockages promptly. Traditional CCTV inspection technologies are slow and relatively expensive so are not well suited to the rapid inspection of a network. This is needed if managers are to be able to address sewer blockages pro-actively. This thesis reports on the development of low-cost, rapidly deployable acoustic base sensor that will be able to survey live sewer pipes. The sensor emits short coded acoustic signals which are reflected from any defects of the wall of the underground pipes and recorded for future processing. The processing algorithms are based on the temporal windowing, deconvolution, Fourier, and intensity analysis so that the response can be linked directly to the location and property of the of the pipe deformation. The sensor was tested in a full scale sewer pipe in the laboratory and in few sites in UK, Austria and Netherlands and it was shown that it is able to discriminate between blockages and structural aspects of a sewer pipe such as a manhole and lateral connection. The anticipated cost is orders of magnitude lower than any current technique.