This article deals briefly with the procedure adopted in evaluating aspects and elements involved in selecting the location of the 6 x 600 MW unit thermal Matimba Power Station at Ellisras In the north-western Transvaal.
The geotechnical engineering details of the first of Escom's new generation power stations, with spread footings rather than piles, are descriptionbed. Of particular significance Is the fact that extensive investigation, analysis and resulting design parameters applicable to the major foundation requirements were succeaafully related to the multitude of remaining foundations without further extensive field work. Remarkably large and deep excavations were undertaken to found the heavily loaded structures successfully, although the overall economy achieved in comparison with normally piled foundations was very rewarding.
The effect that the construction of Matimba Power Station would have on this picturesque and sensitive part of the Bushveld and the environment called for drastic measures to be taken with regard to site conservation and preservation. These measures required careful planning and a high degree of control with a fair amount of education, dedication on the part of the team being a major Ingredient. The conservation of the natural assets during the construction process has paid dividends, with the structure today blending well into its surroundings.
The use of rounded 'pebble' coarse aggregates in major civil engineering projects in the Republic is quite unique. When Escom sited Matlmba Power Station in ElIlsras, an area scarce in conventional aggregate materials, the decision was taken to use the rounded colluvial pebbles for concrete aggregate. Both Escom and the contractors' engineering personnel had to become familiar with the very different characteristics of the stone, but combined efforts made the venture technically and commercially successful.
Two different designs were offered for the boiler structure of Matimba Power Station, one being based on concrete pylons with a dimension of 7,5 m x 7,5 m each, the other using steel pylons measuring 2,5 m x 2,5 m. A detailed comparison revealed definite advantages on the part of the steel alternative: lower cost, a reduced construction period and a significant increase In usable floor space between the columns. This article gives details of the steel structure design principles and also refers to manufacture and erection procedures that had to be adapted.
The paper descriptionbes the background to the current method of procurement of chimneys by Escom. Features of the design/construct specification, tendering and appraisal procedure, particular design review and foundation details are highlighted. This method of procurement has been used on numerous chimneys over the past six years and has proved very satisfactory.
The turbine house structure is subjected to heavy industrial plant loadings. Associated imposed floor loadings are not covered In the SABS design codes. This paper descriptionbes the structural concept and design loads used. Restraint actions due to temperature variation, shrinkage and settlements are considered. The design was done In 1982/83.