2007 – Current international state of practice for the seismic design and analysis of appurtenant structures at dams
Steve O’Brien
Appurtenant structures associated with a dam play and important part to the dam’s operation. For these structures it may be important that their functional and structural integrity is retained in the event of a notable earthquake, particularly when they are required to release water from the reservoir in a controlled manner to lower the storage following an earthquake. Research has been conducted into the current state of practice for the seismic design and analysis of these structures, including review of the main issues for seismic effects, documentation of case histories and review of current research, international guidelines and standards. The general assessment philosophy was found to be relatively consistent internationally, however, the adopted assessment procedures were found to vary. The status of the current ANCOLD earthquake guidelines has been provided in relation to the current international state of practice for various types of appurtenant structures.
Keywords: Appurtenant structures, performance criteria, seismic performance, seismic analysis.
$15.00
Related products
-
$15.00
Papers 2007
2007 – The geotectonics and geotechnics of the Traveston Crossing Dam foundation
Learn moreMike Marley, Greg Dryden, Geoff Eades, Edwin Brown, and Gary Huftile
Traveston Crossing Dam is proposed for construction at AMTD 207.6 km on the Mary River, about 25 km upstream of Gympie in South East Queensland. The Mary Valley at the dam site is located in a zone of complex geology resulting from formation in a tectonic accretionary wedge setting. This has been responsible for its complex geological structure, which has required a range of geological and geotechnical investigation and interpretation techniques to develop a model on which to base the dam’s preliminary design. This paper describes the tectonic history and the innovative techniques used in developing the geological model for the dam foundation.
The investigation involved aerial photograph interpretation, geological mapping; geotechnical drilling, including water pressure testing; seismic refraction profiling; downhole geophysical logging; excavation and geological mapping of large excavations; and hydrogeological investigation involving investigative drilling and pumping tests.
A Vulcan 3-D computerised geological model was constructed using borehole data, seismic refraction interpretation and downhole geophysics interpretation. The geological model has been used in the development of the preliminary design and confirms that the foundations are suitable for the proposed structure.
Keywords: Dam Foundation; Geophysics; Investigation Tectonics; Geological Strength Index Kinetic Analysis
Learn more -
$15.00
Papers 2007
2007 – Comparison of New Zealand and North American dam anchoring practices
Learn moreStephen McInerney, Donald A. Bruce and John Black
An historical database of North American dam anchoring experience has been recently assembled in the United States. This database clearly shows the historical development of dam anchoring technology, particularly with regard to corrosion protection practices over four decades. The results of this research are significant to dam owners worldwide because of the number of examples in the database.
The paper describes New Zealand experience with dam anchoring against the background of the historical practices in North America and the main conclusions drawn from the United States research.
Keywords: Post-tensioning, anchor, corrosion protection, historic database, dam remediation
Learn more -
$15.00
Papers 2007
2007 – Improving safety and hydraulic efficiency of dams with physical model studies
Learn moreSteven L. Barfuss and Blake P. Tullis
An important aspect of improving the safety of dams is selecting designs that are both hydraulically efficient and cost-effective. A powerful tool that can be used as part of the hydraulic structure design process is a physical model study. To obtain maximum benefit from the model, it should be implemented as a part of the design process rather than as a post-design verification phase. A model study included early in the conceptual design phase can also provide increased flexibility to the designers.
Hydraulic model studies can often provide cost-effective answers to difficult problems. Some of the issues that can be efficiently resolved using model studies include optimizing spillway head-discharge relationships to increase reservoir storage while minimizing upstream flooding potential, controlling downstream scour, quantifying hydraulic uplift forces and/or overturning moments of dam structures, evaluating alternatives for structure retrofit or repair, and optimizing control gate sequencing during floods. Model studies also allow the engineer to simulate prototype performance (e.g., three-dimensional flow patterns, velocities, pressures, scour potential) over the full range of expected discharges. Quick and easy changes to the model can be made at minimal cost when evaluating the performance, safety and economic impact of various design alternatives.This hands-on model study approach to dam safety represents a tool that in some cases is underutilized.
Brief discussions of several physical model studies conducted at the Utah Water Research Laboratory, Utah State University in Logan, Utah, USA, are presented to illustrate key points of the paper. The primary objective of each of these model studies was to provide and/or improve the safety of the dam and the spillway while minimizing construction costs. This paper discusses the cost-effectiveness and hydraulic improvements that can be achieved through physical model studies.
Keywords: Physical models studies, design, hydraulic efficiency, dam safety, construction costs
Learn more -
$15.00
Papers 2007
2007 – Wave seiching and run-up effects in Lake Aviemore due to seismotectonic displacement of the lakebed
Learn moreM.G. Webby, C.J. Roberts and J. Walker
The Waitangi Fault passes under Aviemore Dam and Lake Aviemore in the Waitaki Valley in the South Island of New Zealand. Several studies were undertaken in the period 1999-2004 to understand the geology and faulting in the Waitaki Valley and, in particular, to determine the potential for future movement on the Waitangi Fault (Walker et al. 2004). As part of the Aviemore Dam Seismic Safety Evaluation (ADSSE) Project, a numerical hydrodynamic study was undertaken to analyse the pattern of seiche waves generated by fault displacement and to determine the potential wave run-up on the dam face to overtop the dam.
Ground displacement along the Waitangi Fault gives rise to initial wave trains on the lake surface travelling in opposite orthogonal directions away from the fault line and approximately parallel to the axis of Aviemore Dam. These initial wave trains are refracted by the lakebed as they approach the eastern and western lake shorelines and are then reflected off these shorelines. The reflected wave trains interact to create a very disturbed lake surface before a long-period seiching response is set up due to repeated lakeshore reflection. The seiching response is a bimodal one, with a cross-lake component and an along-lake component. The along-lake seiche waves run up on the relatively steep embankment part of the dam and on the vertical face of the concrete gravity part.
Keywords: Seismotectonic, fault, displacement, lake, dam, numerical, hydrodynamic, model, seiche, wave, solitary wave, wave run-up, dam overtopping.
Learn more -
$15.00
Papers 2007
2007 – Upgrade of the Aviemore spillway and sluice gates for dam safety operation
Learn moreKen Ho, Robert Davey and Jim Walker
The Aviemore Dam appurtenant structures were upgraded for seismic performance in 2006. A comprehensive dam safety review programme conducted by Meridian Energy evaluated the performance of the dam and appurtenant works under extreme ground movements and rupture displacements of the Waitangi Fault, which passes through the embankment dam foundation. The spillway and sluice gates are key elements of the dam safety critical plant for the passage of floods to prevent overtopping or emergency dewatering of the reservoir after a major seismic event if there are concerns about damage to the dam. This paper outlines the assessment undertaken for the spillway and sluice gates for seismic performance and the upgrade necessary to safeguard their integrity for operation after the event.
The spillway and sluice gates are large steel radial gates operated by electrically powered wire rope winches and hydraulic actuation, respectively. Combined hydrostatic and the Safety Evaluation Earthquake (SEE) induced hydrodynamic loads would be expected to stress the gate structures beyond their yield capacity. The yield would be downstream only due to the influence of the hydrostatic load under the earthquake response cycle. The resulting deformations were predicted to fracture connecting bolts in the spillway gate arms and cause severe leakages past the top leaf of the sluice gates. The solutions developed for the spillway gates to reduce connection bolt damage and the strengthening of the sluice gates will ensure their post-earthquake operation.
Keywords: Aviemore Dam, spillway, sluice, radial gate, seismic performance, post-earthquake operation.
Learn more