INTERVIEW | TARCISIO B. CELESTINO
“With Themag, I worked on
hydroelectric power plants and they involved underground works. There was one project in particular that I would like to mention because it sparked one of the interests in my career. It was almost at the beginning of my time with the company – it was the underground powerhouse for a hydroelectric power plant, Paulo Afonso IV. Another company, not ours, had designed it; and the width required for the turbines in the cavern hall was 26m. The lining of this turbine hall was very heavy, however. It was designed as a 2m-thick arch of heavily reinforced concrete, cast insitu. “Unfortunately, it was an unfeasible
design, and it was already being constructed. The contractors ran into difficulties. The scale of excavation required – a 32m-span (105ft) – was too large for the site along with the heavy concrete arch. Eletrobras, which is the federal government organization for hydroelectric power in the country, realized that the design was unfeasible and put a stop to construction, and also put a hold on the power company developer’s licence. “They hired Themag, the company I was
working for, to sort it out, to remedy the situation. Of course, I had nothing to do with that; I was just a young engineer. But I was very fortunate to have been involved with the company then to learn, for they decided to change the design completely. Instead of a a 32m-span (105ft), the cavern excavation ended up as only 26m (85.3ft); and, the change was possible because the new design used sprayed concrete lining, which the original design had not considered. Instead of a 2m-thick concrete arch, therefore, a 150mm-thick shotcrete shell and rockbolts were adopted for the reduced span of the powerhouse cavern excavation. “So this material, this so-called shotcrete,
caught my attention when I was a young engineer, and I saw that it enabled a design that was only made feasible because of it. So my interest in sprayed concrete started right there, even though at that time I did not even know what it exactly was. Later on, on designs with which I have been involved for conventional tunneling, the use of sprayed concrete has often been central to the solution. “Another area of work for which I have
Above:
Being active in both academia and consultancy is a combination that has created many exciting and technically interesting opportunities for Tarcisio B. Celestino
24 | Winter 2023
been involved, as a consultant, is a rock salt solution mining project underneath part of an important city in North-eastern Brazil. Subsidence became a serious problem and the owner decided about four years ago to
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