Ferreira Street Offices

The building has of two underground basement parking levels with five floors of offices above. The total floor space provided is 10 300m².
Soil-nailing was used in the construction of the basement where the excavation was ±8m deep with adjacent buildings in close proximity. The system consists of drilling holes downwards at 10 degrees to the horizontal into the ground, installing steel rods into the holes and encasing the rods with grout. The face of the excavation is covered with gunite (shotcrete) – reinforcement is placed within the gunite layer. Construction, including excavation, proceeds from the top of ground level downwards in stages of 1 to 2m.


Tensile stress is applied passively to the steel rods in response to deformation of the retained soil during subsequent excavation activities. The grout transfers stress from the ground to the rod anchors and provides corrosion protection. A bearing plate at the end of the anchor transfers the force to the concrete facing. In this case the gunite facing forms the permanent retaining wall which is also braced by the upper floors which were cast directly against the wall. Vertical drainage strips are installed behind the facing onto the excavation face (prior to guniting) which serves to collect and transmit ground water to a toe trench. This method of constructing the basement proved to be cost-effective and fast.
Conventional  foundations were cast on the rock which occurs at the bottom of the basement. Flat slab construction was employed utilizing both coffers and solid 255mm slabs.   

Additional Info

  • Province: Mpumalanga
  • City or Town: Mbombela
  • Project Date: 2008 to 2009
  • Project Value: R 50 000 000
  • Client Name: Private Developer
Last modified on Wednesday, 20 November 2013 08:37
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