Thesis (MEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Segmentally lined tunnels are increasingly being built to transfer water from one water
scheme to another. The segments that line such tunnels are often in the form of pre-cast
concrete sections, which are placed around the perimeter of the tunnel.
As these tunnels are very expensive to construct, it is imperative that their hydraulic
capacities can be calculated accurately. Even a slight variation in the design diameter has a
significant effect on the cost of the tunnel.
Due to the construction method involved, alternative segments are not always properly
aligned. This creates roughness elements in the tunnel commonly known as steps. These
steps occur randomly and vary in size. Since the steps lead to increased roughness and thus
decrease the hydraulic capacity of the tunnel, it is essential that this effect be allowed for in
the design of the tunnel.
A hydraulic model was used to determine the contribution of steps to the hydraulic
roughness, according to step size and frequency of steps. / AFRIKAANSE OPSOMMING: Tonnels word al hoe meer gebou om water tussen waterskemas te vervoer. Die voering
van sulke tunnels word dikwels saamgestel uit voorafvervaardigde beton panele wat
geplaas word om 'n huls langs die omtrek van die tonnel te vorm.
Aangesien hierdie tonnels geweldig duur is om te bou, is dit uiters noodsaaklik dat die
hidrouliese kapasiteit van 'n tonnel akkuraat bereken kan word. 'n Klein variasie in die
diameter van die tonnel het 'n betekenisvolle effek op die koste daarvan.
Die konstruksiemetode van sulke tonnels veroorsaak dat opeenvolgende panele nie altyd
presies oplyn nie. Sulke afwykings in die belyning van die tonnelpanele veroorsaak klein
trappies, wat bydra tot die ruheid in die tonne I en sodoende die kapasiteit daarvan laat
afneem. Die afwykings varieer in grootte en kom in geen spesifieke patroon voor nie.
'n Modelstudie is uitgevoer om die bydrae wat die afwykings in the belyning van die
opeenvolgende ringe tot die hidrouliese weerstand maak, te bepaal.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53062 |
| Date | January 2002 |
| Creators | Bester, J. W. |
| Contributors | Rooseboom, A., Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 1 v. (various pagings) : ill. |
| Rights | Stellenbosch University |
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