Transverse cracking in embankment dams resulting from cross-valley differential settlements

Abstract

This article investigates transverse cracking in embankment dams resulting from cross-valley differential settlements during and post-construction, in which concentrated leak erosion may initiate. Based on case studies and numerical analyses, it is shown that valley profiles with a step in the upper part of the abutment and subject to large post-construction settlements within the embankment, or within compressible soil in the foundation, are most likely to be subject to cracking. Estimated localised strains at the crest > 1%, and in particular >2%, are likely to be indicative of conditions conducive to transverse cracking. Smaller strains but greater than about 0.25% may also result in cracking but they are likely to be narrower and shallower. The article also gives general guidance on the likely width and depth of cracking. The information presented is only suitable for preliminary dam safety assessments. For detailed dam safety assessments and risk assessments where decisions are to be made on whether risks are tolerable, or upgrades required, site-specific cross-valley numerical analyses should be carried out. These detailed analyses should model the cross-valley profile accurately, material parameters more rigorously than has been done in the parametric studies reported in this article.

Keywords:

• Embankment dams
• differential settlements
• transverse cracking
• internal erosion and piping

Acknowledgement

Goulburn-Murray Water provided data on Buffalo Dam and US Bureau of Reclamation data for Red Willow Dam.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was carried out with funding provided by Australian Research Council Grant Number LP110100389, University of New South Wales, Department of Public Works, Dam Safety Committee of New South Wales, Murray Darling Basin Authority, Water Corporation, Southern Water, now TasWater, Hydro Tasmania, Melbourne Water, Goulburn-Murray Water, SunWater, URS Australia, now AECOM, GHD, SMEC Australia and Elforsk.