n Journal of the South African Institution of Civil Engineering = Joernaal van die Suid-Afrikaanse Instituut van Siviele Ingenieurswese - Hydraulic roughness of bored tunnels - : technical paper

Volume 40, Issue 4
  • ISSN : 1021-2019



This paper presents the results of a research project carried out at the University of Natal, Durban, in 1994/95. The topic was the hydraulic roughness or resistance of unlined, bored water tunnels. Physical roughness data from various bored tunnels were collected. An in-depth investigation into energy losses in conduits and the associated mechanisms was made. The roughness date were analysed and linked to these energy loss mechanisms, to predict the expected hydraulic friction effects. A similar investigation was made on the inner surface of spun concrete pipes, and the results predicted accurately matched those obtained by physical roughness data was developed. Recommendations are made for attaching estimates of hydraulic resistance encountered in tunnels bored by machine through various rock types.

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