Ahmad Shayan, Robert J. Wark and John Waters
The Canning Dam concrete gravity structure located in Western Australia has shown an upward movement of 18.3 mm and lateral upstream movement of 14.2 mm over the past 15 years of monitoring. These movements have been associated with considerable cracking of the upper parts of the dam and the upper gallery. Investigations have shown that the cause of the cracking was a strong alkali-aggregate reaction (AAR) in the concrete, brought about by a deformed granitic rock. Extensive horizontal and vertical cracking in the upper part of the dam wall has necessitated the removal of the section above the floor of the upper gallery level, and construction of a new reinforced concrete section to act as head beam for post-tensioning of the rest of the dam wall.
A set of small diameter cores were taken from the various parts for diagnostic purposes, and a vertical core of 100 mm diameter was taken through the whole thickness of the wall for the determination of the strength properties, alkali content and residual expansion potential. Based on these, a post-tensioning stress of 1.5-2.0 MPa has been calculated for restraining the residual expansion of the concrete. The spillway bridge structure which is part of the dam wall has also shown mild signs of deterioration. The piers and abutment walls and the deck were surveyed for corrosion activity and extent of AAR. This work showed that the spillway bridge structure was sound and only needed maintenance. The performance of a triple blend concrete mix containing a high volume of fly ash (45%) and silica fume (5%) developed for the replacement of the old concrete is also discussed.
Now showing 1-12 of 33 2963:
Among the major energy options, Large Hydro Power is considered to be the front ranking and renewable. But, in most of the developing countries including India, the large multipurpose dam
projects are shrouded in controversies.
This paper, while dealing with positive and negative impacts of large multipurpose dam projects, Jocuses on Social Impact Assessment’ and its mitigatory measures, for the success of the project. The Environment cost as well the Human cost of such projects should be judiciously integrated in the project cycle from its conception to its post implementation stage, for sustainable development of this
Peter Quinlan and Sergio Giudici
The Hydro Electric Corporation (HEC) owns and manages 54 large and referable dams across Tasmania. Monitoring, data storage and data utilisation techniques have evolved significantly over the years as the dams have aged and as instrumentation, communication and data management technologies have advanced. This paper describes the development of the HEC’s ‘Asset Safety Evaluation Tool’ (ASET) for acquisition, management and interpretation of data relating to dam safety management. The paper also provides examples of how ASET has been applied within the HEC to demonstrate how the primary functional development goals of robustness and practicality have been achieved.
Douglas Gallacher, Richard Doake and Debbie Hay-Smith
Damage to the rip-rap protection on the upstream face of Megget Dam has occurred since first filling in 1983 and independent wind-wave investigations have demonstrated that waves exceeded anticipated wave heights. Value Planning Studies for alternative schemes to upgrade the rip-rap protection indicated that bituminous grouting was the preferred option and its satisfactory performance was proved by site trials during May 1997. The bituminous grouting works were carried out in two stages with a break over the winter season. The upper part of the face was completed over a 12 week period (September to early November 1997) and the grouting works for the remaining area was completed over a 24 week period (mid April to early October 1998).
Robert E Saunders
The vast majority of dams in Australia are relatively small affairs. For example, approximately 90% of Queensland’ referable dams are less than 15 m in height. Most of these dams are owned by small communities, mining companies or farmers, many of which have smaller operations than those of Australia’s larger dam owners. In many cases the dam represents the owner’s sole source of water supply.
Many smaller dam owners are unaware of the key factors affecting the safety and best management of their facilities. Added to this is a general lack of understanding of dam related issues by the community at large. This often leads to significant owner and community concerns (and conflicts) that have the potential to jeopardise the viability, or worse, the safety of a project. The relative importance of the dam to the smaller dam owner often exacerbates these issues.
This paper serves to illustrate, by way of example, a consultant’s viewpoint of some of the issues encountered on small dam projects and suggests actions that the dams industry as whole could take to improve the situation.
Gary Hargraves, Russ McConnell and John Ruffini
The acceptance of the use of generalised methods for estimating extreme rainfall has resulted in a growth of the Probable Maximum Flood (PMF) estimates that spillways of dams are required to pass. In many cases spillways were not designed with spare capacity and are incapable of safely passing the new PMF estimates. Dealing effectively with the potential for dams to cause damage and loss requires a risk management approach. Such an approach requires more reliable tools for estimation of rainfall. This paper examines the issues, the progress made, and outlines further work and options for clarifying risk.