Nestled in the scenic vineyards south of Stellenbosch, Alto Winery is undergoing an ambitious upgrade to enhance its winemaking infrastructure. A key component of this transformation is the construction of a new basement, designed to increase storage capacity on-site. This addition required innovative geotechnical and structural engineering solutions, particularly in terms of lateral support and foundation piling.
Geotechnical challenges
The Alto Winery site is characterised by shallow, medium to coarse-grained granitic soil from the Kuils River Batholith, part of the Cape Granite Suite. These granitic formations are overlain by sandy colluvium and localised fill, forming the upper 1,3 to 2,3 metres of the subsoil profile.
Due to the soil conditions and the large size that conventional spread foundations would have required, a piled foundation system was selected as the more suitable solution for the project.
Engineering solution
Franki Africa was appointed to deliver both the lateral support system and the piling solution. The lateral support for the 5,8 m cut was designed as a hybrid system comprising soldier piles and grouted anchors. These elements work in tandem to stabilise the excavation face. The soldier piles were connected by a continuous capping beam, ensuring uniform load transfer.
A key engineering challenge was the close proximity of the excavation to the existing structures. The carefully designed and executed lateral support system successfully limited ground movement during and after construction.
Once the lateral support system was installed, excavation to the basement level commenced. This excavation served as the platform for the installation of Continuous Flight Auger (CFA) piles. The foundation design included a grid of piles interconnected by ground beams, tailored to support the structural requirements of the new storage facility.
