Construction World September 2016

GEOTECHNICAL

in Windhoek LATERAL SUPPORT Source: Niel de Klerk The new office of the Prime Minister of Namibia is being constructed next to the existing Ministry of Finance building. The site location overlooks the city of Windhoek from a hilltop and inspired the architect’s vision of designing an environmentally friendly building, rising out of the Khomas Hochland. >

Furthermore, in order to minimise its geographical footprint, the multi-storey building will have a basement staff car park. Analysis of the mica schist (a crystalline metamorphic rock) formation was under- taken by Stefanutti Stocks Geotechnical and its design engineer, and indicated that the material dipped in a northwesterly direction. This meant that the excavation’s southerly and easterly walls would be most vulnerable and as the excavation will also be at its deepest here (18,9 m high at its highest point with a 200 mm thick off-the-gun gunite

finish) precise lateral support is required. Bulk earthworks and site preparation for the building saw a total of 53 000 m 3 of rock removed. However, as the excavations progressed the soil conditions required the appointment of a blasting contractor. Some 10 000 m 3 of hard rock was blasted over weekends due to local blasting regula- tions (which specify the evacuation of within a 500 m radius) and the site’s proximity of the Ministry of Finance and Parliament. Once the excavations were completed Stefanutti Stocks Geotechnical began with the installation of the lateral support to

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EYE-CATCHING RETAINING WALL

Auas Hills Retirement Village, situated in Auasblick, is a sought after Retirement Village in Windhoek.

It provides a tranquil setting and caters for all the needs of the more senior citizens, providing facilities

retaining walls, in case of heavy water run-off during the rainy season. In total around 25 000 blocks were installed.” The project was completed in Febuary 2015, with landscaping by Andre’s Landscaping adding the final touches to the walls.

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like a well equipped restaurant where you can enjoy nice meals, an onsite laundry, a day care centre, pharmacy, physiotherapist, biocineticist and a high care centre (should it be necessary). During the planning stages it became evident that earth retaining measure would be needed to stabilise the exposed embank- ments resulting from excavation activities. Steffanuti Stocks, the main contractor on site, approached Namwall, Windhoek based Namibian licensee for Terraforce, to provide a design for Terraforce block retaining walls. Says Chris Schutte, of Namwall: “We consulted with Terrasafe, Terraforce’s profes- sional design service, and had a design ready in no time. Most of the proposed rock face block walls were pretty straight forward, with the higher ones requiring a double skin of L12 blocks for extra reinforcement. In addition to the walls inside the property, a river running alongside the retirement village needed erosion control

CONSTRUCTION WORLD SEPTEMBER 2016