As construction development continues apace in Sandton, dubbed the new financial district of South Africa, specialist geotechnical contractor Franki Africa has made a leading contribution to the provision of geotechnical solutions for decades of development within the Sandton Central Business District.

Sandton was officially established in July 1969, deriving its name from a combination of two of its suburbs, Sandown and Bryanston. At that time Sandton was primarily a residential area made up of a few suburbs comprising mainly smallholdings. The construction of Sandton City in the early 1970s was the first major development in the area and other landmark developments quickly followed as a result of the urban decay in downtown Johannesburg, historically the province’s main business hub.

Franki Africa supports decades of Sandton development

The ongoing decline in the Johannesburg CBD led to a veritable exodus of large corporates to Sandton in the 1990s, establishing it as the new financial district of South Africa and enabling it to take over the title of Johannesburg's premier business centre.

Specialist geotechnical contractor Franki Africa has made a leading contribution to providing geotechnical solutions for decades of development within the Sandton Central Business District (CBD). “Our first job in the ‘the northern suburbs of Johannesburg’, an area that would later be called Sandton, in 1960 was for a private residence and involved installing 53 piles approximately 4’6” in length that were hand dug,” recalls Mike Taitz, divisional director at Franki Africa.

Since then, Franki Africa has been involved in landmark developments such as the Michelangelo Hotel, the Johannesburg Stock Exchange, Sandton Gautrain Station, Discovery and Sasol Offices.

Challenging conditions

The Sandton area is underlain by highly undulating bedrock granite with residual granite on top of it. As a result of irregular weathering patterns in this granite, the level of rock is neither constant nor continuous. In addition, the area is punctuated by numerous diabase dykes resulting in the formation of large boulders and hard rock spheroids within the residual soil. Due to the complex geology, a variety of solutions have been developed to counter these challenges and make the developments economically viable.

“For the 100 Grayston project, we anticipated the presence of diabase boulders on the southern portion of the site,” says Brett Markides, senior design engineer at Franki Africa.  “We had to work closely with the engineers and project team to develop solutions as the work progressed to ensure the project remained on budget and on programme.”

The 100 Grayston project is an extension to the Investec Head Office in the heart of Sandton CBD. The development comprises a multi-level office block with a double basement level. Franki was awarded the tender for the design and supply of lateral support works and foundation piles to accommodate varying loads up to 12 000 kN.

According to Dr Nicol Chang, technical director at Franki Africa, it is important that high quality geotechnical investigation be carried out during the planning phases of these projects. It is clearly evident from numerous publications that cost overruns (or construction cost) for geotechnical projects reduces significantly with increased site investigation. “Accurate predictions of design and cost can only be produced when the professional team has full confidence in the conditions of the ground,” says Dr Chang.  

Prominent projects

Franki Africa was involved in several phases of the later development of Sandton City from 1990 to 1992, including blasting, excavating and installing lateral support to create a new cinema complex beneath the shopping centre.

Other prominent projects during the 1990s include the Nedbank Group headquarters development that spanned an area from Maude to Fredman Drive and is still one of the biggest projects of its kind in Sandton to date; the Hilton Hotel; the Johannesburg Stock Exchange; Deutsche Bank; Sandown Village; phases of Investec headquarters; Sandton Square; various international embassies; the Michelangelo Towers – the tallest building in Sandton; and the Rand Merchant Bank headquarters.

More recently, Franki Africa has successfully completed projects that include the Sandton Gautrain Station; the Radisson Blu Gautrain Hotel; Alexander Forbes headquarters; the Ernst & Young headquarters; Phases 1 and 2 of the Standard Bank development in Alice Lane; Morningside Clinic; Old Mutual; as well as new headquarters for Webber Wentzel, Werksmans Attorneys, Sasol and Discovery.

Tight programmes

Today developments being rolled out with ever tighter timelines and requests for partial site handovers are becoming the norm. Franki Africa understands how to design and manage these solutions to navigate a critical path for the project. “The 100 Grayston project is extremely challenging,” says Paulo Alves, senior contracts manager at Franki Africa.

“The site is located in one of the busiest areas in Sandton with numerous services (known and unknown) along Rivonia Road and Grayston Drive, which needs to be taken into account in the design. With the assistance of a strongly experienced site team, continuous design development on the lateral support can be undertaken to accommodate the on-going challenges.”

In addition to the tight construction programme, new developments require deeper basements to accommodate parking requirements. Excavations in excess of 20 m are now commonly required, and as deep as 34 m was carried out for the Discovery headquarters. This often requires blasting and support during the construction phase and Franki Africa has developed technology and products to do all the necessary geotechnical support. 

Market leader

Franki Africa is the largest, oldest and most established specialist geotechnical contractor in sub-Saharan Africa, offering a comprehensive range of services which ensure that its customers benefit from the most cost-effective solutions for their geotechnical requirements.

Franki operates in sub-Saharan Africa and the Indian Ocean Islands and, together with Keller, has the experience, capability and capacity to undertake projects of all sizes.  The comprehensive product range at Franki is further enhanced by its in-house geotechnical Design Capability. Being part of Keller (www.kellerholding.com) also widens the company’s product range, capacity and capability.

Franki offers a comprehensive range of geotechnical and marine engineering services, including both design and construction for the general construction, civil engineering and mining industries. Franki is certified in accordance with ISO standards for Health & Safety,

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