Page 48 - SAICE book proof 2 LATEST JULY 2014

s a i c e GAUTENG PROVINCE

18. Trust Bank Basement. The 31 m deep base- ◊ Below: Trust Bank
ment of this building was the deepest of its kind at ◊ Below Centre: Carlton Centre
the time of construction and civil engineering history ◊ Bottom: Standard Bank
was made by the civil engineering team who designed
the structure which had to abide by the rules includ-
ing those of the city engineer who temporarily forbade
the use of anchors since he was of the opinion that
the design team who brought this technology of ground
anchoring to Johannesburg, would cause more parking
basements to be constructed and so increase car flow
to and from the city. The concept of a ‘squashed circle’
then emerged – that is, four flat arches tangential to
the sides of the city block and joined by four small arch-
es at the corners. The risk of the flat arches buckling
under the earth pressures brought Dr Ross Parry Davies
and Ruben Stander to develop the concept of creating
four huge flat jacks behind the corners and pressurising
these with cement grout to induce an inward thrust at
the corners and corresponding outward thrust behind
the flat arches.

When putting theory into practice, the designers admit
to having had butterflies in their stomachs each time
they carried out the grouting operation. At a conference
in Mexico in 1969, Ralph Peck expressed interest in the
technique, and at a conference in Tokyo in the early
1990s the Trust Bank was described as being 25 years
ahead of its time.

19. Carlton Centre Basement. This 30 m deep
basement supports a 200 m high office building. Exca-
vations started in 1967 and have a 20 000 m² footprint.
The excavation took place in the middle of the city cen-
tre in between four streets where bracing systems and
dewatering systems were extremely important. The
bracing grid is supported on 200 piles. Currently used
as a parking garage, very little can be seen of this ma-
jor engineering achievement.

26°12’20.26” S, 28°02’47.85” E

20. Standard Bank hanging office floor build-
ing. This unique 34-storey office block reaching a
height of 139 m was designed in such a way that three
sets of office floors are suspended from concrete beams
radiating from the centre core at various levels.

26°12’24.19” S, 28°02’22.09” E

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