2007 – Safety evaluation of a slab and buttress dam

Marius Jonker, Francisco Lopez and John Bosler

This paper describes the safety evaluation and development of remediation options for Clover Dam, a 28 m high slab and buttress structure situated in the alpine region in northeast Victoria, Australia. The review was particularly challenging considering the complexity, age and cracked condition of the dam structure, which required the development of an analysis method for this type of dam.

Completed in 1953, Clover Dam is one of five dams in the Kiewa hydroelectric scheme. The 76 m long dam comprises a 45.7 m long covered slab and buttress section, supported on each abutment by concrete gravity sections. The review was undertaken as a result of severe cracking occurring since the early 1970s and because a detailed design review had not been undertaken since its construction.

Current guidelines for the safety review of existing dams provide little detailed information on slab and buttress dams. Consequently, a methodology was developed to analyse Clover Dam. This methodology could also be applied in the review of this type of dam in general, and is currently being used for safety assessments of three other slab and buttress dams.

This paper focuses mainly on the dam structural assessments undertaken during the safety review. The structural analyses involved 3-D finite element analyses for thermal, static and earthquake loading.

The outcome of the review was that both the gravity and buttress portions of the dam do not meet current design standards. The development of practicable remediation options was complicated by the operational constraints and the restricted access to those areas within the dam where remedial works were required.

Keywords: Slab and buttress dam, 3D finite element analysis, seismic assessment.