Stresses in cast-iron pipes due to seasonal shrink-swell of clay soils

Abstract

The causes of pipe damage that lead to leakages and bursts in water distribution networks are numerous, and the significance of each possible mechanism is not yet fully understood. This paper reports field monitoring and numerical modelling carried out to evaluate the potential for vegetation-induced desiccation to impose significant bending and therefore additional stress on buried water pipes. Over a period of two years, vertical and horizontal deflections were measured along two flexible pipes buried in London Clay in the vicinity of an oak tree. Meteorological measurements made at the site allowed soil moisture deficit to be computed, and these values were compared with regional values supplied by the UK national meteorological office. Finite difference continuum analyses were carried out in order to permit the interpretation of measured deflections in terms of the equivalent stress increases that would be imposed on a rigid cast iron water pipe. The calculated maximum tensile stress increase was found to be significant in terms of the residual strength of a corroded cast iron pipe.

Geotechnical evaluation of the alluvial soils for urban land management zonation in Gharbiya governorate, Egypt

“…Yet, changes to the volume and the Cl À and SO 4 À2 contents of these clays are significant in the arid and semi-arid areas justifying their mutual analysis to disclose their geotechnical risks. In these areas, the change of the soil water content is widely related to high evapotranspiration of vegetation that sometimes exceed four times the precipitation (FAO, 1998), brought about by local site changes such as leakage from water supply pipes or drains, or associated with a pattern of short periods of rainfall followed by long dry periods resulting in seasonal cycles of soil swelling and shrinkage (Nelson et al, 2001;Cameron, 2006;Clayton et al, 2010). However, the geotechnical tests that are widely performed to understand the potential problems of soils can be time-consuming, expensive, and limited.…”

A two stage model for moisture-induced deformations in expansive soils

“…The effect of these alternate movements exhibits differently under various types of covers. For example, longitudinal cracks in highway embankments (Jotisankasa et al 2011), heaved domes in residential basements , settlement in the vicinity of trees (Driscoll 1983), and vegetation induced movements in pipelines (Clayton et al 2010). The cost of infrastructure repair is comparable to other natural disasters such as the estimated $1 billion in the United States of America (Phanikumar and Sharma 2006).…”

Editorial

“…The fifth paper (Rao et al, 2010) continues with the water quality theme but focuses on the issue of drinking water quality, evaluating the use of magnesium oxide in India to reduce excessive fluoride levels. The final paper (Clayton et al, 2010) is concerned with the issue of leakage from water supply pipes and evaluates the contribution due to tree root-induced desiccation of clay soils.The paper by Huong et al (2010), analyses the issue of heavy metal contamination of river sediments in Hanoi, Vietnam. The environmental impact of this industrial wastewater pollution is high as the rivers are the main source of irrigation water for suburban agricultural land and feed water sources for fish farming ponds.…”

“…The fifth paper (Rao et al, 2010) continues with the water quality theme but focuses on the issue of drinking water quality, evaluating the use of magnesium oxide in India to reduce excessive fluoride levels. The final paper (Clayton et al, 2010) is concerned with the issue of leakage from water supply pipes and evaluates the contribution due to tree root-induced desiccation of clay soils.…”

“…The causes of pipe damage that lead to leakages and bursts in water distribution networks are numerous, and the significance of each possible mechanism is not yet fully understood. The paper by Clayton et al (2010) evaluates the potential for tree root-induced desiccation to impose significant bending and therefore additional stress on buried water pipes.…”