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.

A coupled discrete element model for the simulation of soil and water flow through an orifice

“…Cui et al [15,16] attributed sinkhole formation to the outflow of pressurized water from a deteriorated underground region of a pipeline and performed numerical simulations based on this process. Van Zyl et al [17] and Alsaydalani and Clayton [18] experimentally studied the fluidization mechanism caused by the outflow of pressurized water from leaking pipes. Although the study of sinkholes due to sewer pipe failure has attracted increasing attention, further studies are needed to obtain a better understanding of the dynamics of the relevant soil-water interactions.…”

Experimental Evidence of Leaks in Elastic Pipes

“…The behaviour of pipe material and the type of crack can affect the leak outflow, whereas no evidence of influence of the surrounding soil is shown by several experimental results (Walski et al 2006;van Zyl and Clayton 2007;van Zyl et al 2013;Bailey and van Zyl 2015). On the contrary pressure is one of the most significant factors influencing leakages in WDSs (Lambert 2002;Farley and Trow 2003;van Zyl and Clayton 2007), thus active pressure control management is widely considered a cost-effective way to reduce losses in the short term (Walski et al 2006).…”

Theoretical Modeling of Pressure and Leakage in Water Distribution Systems

“…However, soils are not generally able to handle the high flow energies of water jets from leaks in water distribution pipes, and non-Darcy flow is likely to occur close to the leaks, possibly in the form of hydraulic fracture and piping. A 'suspended zone' of soil-leak interaction has been observed in experimental studies based on an idealized soil, and there are indications that the suspended zone acts as an energy dissipation mechanism [11].…”