| 75th Anniversary
Left and below: Yusufeli Dam, Turkey
research focussing on the strange behaviour I had seen at Wolwedans Dam, and despite being told initially by one of my external examiners that what I was hypothesising was impossible in concrete, I was eventually able to produce a sufficiently accurate structural representation of the effects measured on the prototype dam. I was thus be able to conclusively prove my theory on the low stress-relaxation characteristics of continuous horizontally constructed fly ash-rich RCC in arch dams.
Consulting company In 1993, I started a consulting company in South
Africa with two partners; Alan Parrock, a geotechnical engineer, and Raimund Miller, a bridge engineer. We combined the first letters of our first names to create ARQ Consulting Engineers, with me leading the company’s efforts in the field of dam engineering. With my background and preference, RCC and arch dams became the company’s primary focus, although we did work on other dam types as well. Coincidentally at around the time I was completing my PhD studies, we were asked to design the 105m high Changuinola 1 Dam in Panama. With a crest length of over 600m, the site was not obviously suitable for an arch and we originally designed the structure as a gravity dam. When the contractor made his survey on site with the trees cut down, he not only found a substantially wider valley bottom, but gullies present on both abutments that meant that the dam needed to be curved. With these conditions, the necessary volume of concrete for the dam construction increased by over 25%, the cost of which was the responsibility of the EPC contractor. With limited expectations, I raised the option of
reducing the concrete volume by redesigning the central part of the dam as an arch-gravity structure. To my surprise all involved supported the idea and I changed the design to comprise a central arch-gravity structure, transitioning into a curved gravity structure on the right abutment and into a straight gravity section on the left abutment. With an upstream radius
of 525m, the curvature of the arch was not what might have been ideal, but a good structural function was confirmed through analysis. Instrumenting Changuinola 1 Dam and being
involved in processing instrumentation data over the subsequent years provided me with very significant information on the behaviour of low stress-relaxation creep RCC through the hydration cycle and after all hydration heat is dissipated. All recorded behaviour confirmed the findings of my PhD and enabled me to develop an even deeper understanding of the associated effects, which have transformed the understanding of the requirements of thermo- mechanical analysis for RCC dams. The value of these developments was recognised by ICOLD in 2018 with my receipt of the ICOLD Innovation Award at the Vienna Congress.
Project of a lifetime A short time after completing Wolwedans Dam,
a senior member of the dam community in South
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