Soil fluidisation outside leaks in water distribution pipes – preliminary observations

Abstract

This paper reports on a preliminary study carried out to investigate the effect of soil, and particularly fluidisation of soil, around leaking water pipes. During the study a bed of particles is fluidised at controlled flow rates, using upward-pointing orifices to simulate holes in a pipe. The extent of the fluidised zone and the head drop within the bed are monitored. The results show that significant head can be sustained in a shallow pipe without the fluidised zone breaking through the bed surface. Head loss from a leaking pipe is divided into three components: through the orifice; in the fluidised/mobile bed zones; and through the static soil. The results show the extent of fluidised and mobile zones appears to be almost independent of the orifice size. Most of the head loss is found to occur within fluidised and mobile zones; significant (but lower) head loss is found to occur through the orifice and only a small fraction of the total losses occurs in the static soil.