2497x
001229
2022-02-10

Lesotho Highlands Water Project - Construction of Polihali Diversion Tunnels

The Lesotho Highlands Water Project is a multi-phase binational project carried out by the Kingdom of Lesotho together with the Republic of South Africa.

This project aims at harnessing the water resources of the Lesotho highlands by building numerous dams and tunnels. Phase II includes the construction of a dam, transfer tunnel, and associated infrastructure. The Polihali diversion tunnels were initially set up as part of a construction contract to allow for early river diversion in the main Polihali Dam contract.

Dlubal customer Zutari (Pty) Ltd. carried out, among other things, structural analysis of the reinforced concrete inlet structures. Zutari's engineers utilized the RFEM finite element program.

Structure

An optimal solution was developed, including two D-shaped tunnels with diameters of 22.97 ft and 29.53 ft, respectively, and lengths of approximately 0.62 mi each. The tunnels are provided with inlet structures made of reinforced concrete and equipped with stoplog guides, transitioning from a rectangular section to a circular section.

Further transition to the D-shape of the tunnel was constructed using a combination of mass concrete and shotcrete.
The tunnels were excavated using a drill and blast method, full-face, and lined with shotcrete and mesh.

Location
Mokhotlong, Lesotho


Project Specifications

Model data

Number of Nodes 507
Number of Lines 534
Number of Members 38
Number of Surfaces 258
Number of Solids 31
Number of Load Cases 14
Number of Load Combinations 10
Number of Result Combinations 1
Total Weight 10074.750 tons
Dimensions 80.08 x 71.42 x 78.74 feet
Program Version 5.27.01

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