Hydraulic Properties of Small Unlined Rock Tunnels

by Seppo Priha,

Serial Information: Journal of the Hydraulics Division, 1969, Vol. 95, Issue 4, Pg. 1181-1210

Document Type: Journal Paper


The factors influencing the hydraulic characteristics of small unlined tunnel cross-sections are presented. Investigations were carried out in rock tunnels constructed by the Helsinki City Waterworks for conveying raw water. The length of the Silvola Reservoir entrance tunnel is 1.8 km and its theoretical cross section is 4.5 sq m. The length of the Silvola-Vanhakaupunki raw water tunnel is 7.6 km and its theoretical cross section 6 sq m. Vertical shafts divided both of the tunnels into three parts, in all of which cross-sectional measurements as well as pressure loss measurements for different discharges were carried out with measuring weirs and Siemens Venturi meters. All three tunnels were excavated by the so-called Swedish method in the most usual type of rock in Finland, composed mostly of granite and gneiss.

Subject Headings: Hydraulic properties | Rock properties | Cross sections | Water discharge measurement | Pressure measurement | Tunnels | Rocks | Hydraulics | Finland | Europe

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