The latest issue of Dam Engineering (Volume XXIX, Issue 3) has been published. The journal includes a technical paper and two project features (abstracts below):
Field and Laboratory Investigations of the Ageing Effect on a Concrete Arch Dam – An Indian Case Study
by V V Arora & Brijesh Singh
Abstract: There are a large number of important and valuable large concrete dams constructed around the world that are entering “middle age”. There is, therefore, an increasing need to deal with “ageing” concrete in these structures as many of them are nearing 50 years old. In order to execute an accurate and reliable analysis for a concrete dam, a complete chemical and physical analysis of its concrete properties is required. In the present study the abnormal behaviour of a concrete arch dam, e.g. irreversible deformation in the upstream face, upheaval of the central dam crest and floor top gallery, and the formation of continuous hairline cracks on the downstream face of the top gallery are reported mainly to identify the parameters responsible for the abnormal behaviour of the dam, including an assessment of the condition of the material, and also to generate the material properties needed for finite element analysis of the arch dam. The study included physical, chemical and mineralogical properties of concrete for determining the cause of distress in an aged concrete arch dam. Field investigations included non-destructive testing such as an ultrasonic pulse velocity test, a carbonation test, a resistivity test, a half-cell potential test, an in situ moisture content test using a humidity meter, an air permeability test, etc. Laboratory investigations for determining the basic engineering properties of an aged concrete arch dam included compressive strength, tensile strength, Poisson’s Ratio, static modulus of elasticity, drying shrinkage, moisture movement, and coefficient of linear thermal expansion. Studies were also conducted in order to investigate expansion in the dam, which included petrographic analysis, detailed mineralogical analysis covering the absence/presence of reactive aggregates prone to alkali-silica reaction, and a surface morphology study of concrete samples using the scanning electron microscopic (SEM) method, including detection of the presence of ettringite formations and fracture patterns. Based on this study, the possible cause of displacement and cracking in the dam were identified.
The Power of Association
Abstract: The concerns of dam owners extend decades beyond the careful design and construction of their facilities. Operation, maintenance, inspection, and emergency action plans all address long-term safety. Here Ayres Associates in the US discuss the role of floating bulkheads in gate testing and repair, the proper use of rope access and underwater diving in gate inspection, and the use of 1D and 2D modelling in dam-break inundation studies.
Reconstructing Millbrook Dam
Abstract: Otonabee Conservation has embarked upon a major capital project with the reconstruction of Millbrook Dam.
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