Allan J Crichton , Ikhlef Benzenati, Tony J Qiu and Jon T Williams
The Sg Kinta Dam is a 90 m high Roller Compacted Concrete (RCC) gravity dam and is expected to be the first RCC dam in Malaysia when construction commences in 2000. The dam is part of the development of the Ipoh Water supply on mainland Malaysia. A thermal – structural analysis has been completed as part of detailed design using ANSYS finite element analysis software to assess the effect of the heat of hydration of the RCC on resulting structural stresses. The effect of using simple linear elastic material properties on the calculated stresses has been compared to more complex time variant material modulus and creep analyses. From these comparisons it is shown that the simple models overestimate initial stresses and underestimate or cannot predict the long term tensile stresses.
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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.
Buddhima Indraratna, Mark Locke and Gamini Adikari
The main objectives of the filter are to prevent erosion of the dam core, permit controlled passage of seepage flow through the dam and facilitate dissipation of excess pore pressures in the core. In most designs of dam filters, empirical methods based on particle size ratios have been used. These empirical rules are developed through extensive laboratory tests. Although the empirical rules benefit from directly or indirectly incorporating most factors affecting filtration, they cannot be extrapolated for distinctly different soils and do not describe the time dependent changes that occur within the filter medium.
Mathematical models can be formulated to explain the fundamental physics of particle interaction and migration, within a framework of well defined geohydraulic constraints. Considering the mass flow and momentum conservation principles; time dependent changes in particle size distributions, mass flow rates, retention capacity and base soil erosion rates can be simulated.
This paper reviews various empirical and mathematical models, based on the authors experience. A novel approach to large scale filtration is highlighted based on testing actual soil and filter materials from an Australian dam, in a new 500mm diameter apparatus.
The paper outlines the integration of Environmental Risk Management in Goulburn- Murray Water with previous work on Dam Safety, Business and Occupational Health and Safety risks. This has now been followed by the development of an Environmental Management System (EMS) to provide an environmental risk management framework for the whole Authority.
An Environmental Audit in 1997 identified deficiencies in some areas of environmental management and questioned the Authority’s ability to demonstrate due diligence. This led to a decision to develop and implement an EMS based on the International Standard ISO 14001.
Examination of Goulburn-Murray Water activities, associated environmental aspects and impacts, (and the consequences arising), led to the establishment ofan environmental risk register. Analysis and assessment of the risks to produce a ranking Jrom low to very high is described. Refinement to a significant risk register (high and very high risks), and consolidation into a list of generic risks based on major activities, functions and asset categories is described.
Based on this risk profile for the Authority, the Environmental Policy and Objectives were revised, and a methodology for identifying Environmental Targets was developed. Environmental Risk reduction is then delivered through the implementation of target driven Environmental Management Programs (EMPs).
Major system elements described include an emergency response plan, a legal register, an authority / responsibility matrix, a document control system, procedures, forms, training, auditing, and reporting.
The paper describes some of the practical issues encountered and the lessons learned with a focus on the activities of the Headworks Business. A prospective view of implementation and culture change issues is given.
Anthony Moulds and Anthony M Watson
The selection of lightning protection equipment will always remain within the cost versus benefit, or risk management area. As more and more monitoring equipment becomes electronic and microprocessor based, we need to have a better understanding of the ways to protect it, and maintain the data flow.
Recent experience has shown that utilising the Australian Standard (NZS/AS 1768-1991) Lightning Protection, in conjunction with a six-point plan, will go a long way to providing total integrated protection for both structures and contents. However, no matter how much protection is applied, damage due to lightning may still occur. For dam surveillance instrumentation the aim ultimately is to protect the transducer ‘in the ground’ or ‘in the dam’, because generally these instruments are inaccessible and non-replaceable without prohibitive drilling and retrofitting costs.
The six-point plan was applied initially to designing lightning protection for a large, well- instrumented RCC dam, completed in 1991. The protection proved to be not as good as was hoped. The paper describes how the lightning protection at the dam was subsequently developed. This experience, which has pointed the way to achieving a good level of protection at a reasonable cost, has been applied to a number of other, instrumented dams.
Dr. Azam Khan and Dr. Anil Patnaik
Concrete dams are thinner than embankment dams and impose more concentrated loads on the foundation and abutments. A narrow valley with sufficient rock foundation is a typical site for concrete dam, which require a solid foundation that is relatively free of faults, shears, and major changes in foundation strength. Such discontinuities can overstress the concrete by causing some areas of dams to carry more loads than other areas. The measurement of deflections and use of finite element technique can predict the stresses in the concrete dams. A computer model is underdeveloped for prediction of deflections and stresses in Concrete Dam by using finite element. At the first stage of this study, measured deflections from Burrinjuck Dam are compared with the predicted deflections by using finite element. This paper outlines the deflections measured in the dam due to temperature variations and comparison of the measured thermal deflections with those predicted from a finite element analysis.