Title: Design and Prestress Grouting of a Concrete Lined High Pressure Tunnel at Drakensberg

Author(s): Luigi P. Gonano and John C. Sharp

Publication: Symposium Paper

Volume: 83

Issue:

Appears on pages(s): 19-42

Keywords: creep properties; grouting; pressure; prestressing; pumped storage; structural design; tests; tunnel linings; tunnels

DOI: 10.14359/6335

Date: 10/1/1984

Abstract:
Innovative aspects of the design and construction of the concrete-lined high pressure tunnels of the Drakensberg Pumped Storage Project are described. These tunnels located in weak argillaceous rocks are prestressed and designed to remain crack-free at internal pressures up to 6.2 MPa. The extension of an innovative grouting technique developed in Europe provided an economical and technically acceptable alternative to steel liners. Design criteria for structural deformability, prestressing and creep behavior were developed using a prototype-scale test chamber. The design models and practical technology developed for interface grouting will allow the use of concrete linings in pressure tunnels with greater internal pressures and with poorer rock conditions than previously considered feasible.