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CONSTRUCTION WORLD SEPTEMBER 2016
the walls, consisting of 7 200 metres of
temporary soil nails with a permanent
4 170 m
2
gunite wall.
The wall movement of all four walls was
measured weekly throughout the 26-week
duration of the project. This measurement
process, undertaken to guarantee quality,
includes the surveying of fixed points on the
wall by means of a total-station as well as a
plumb-bob system at the highest points of
the walls.
Every morning, prior to work
commencing on site, the plumb-bob system
was measured and recorded in the daily
site diary. Surveying of all wall movement
reflectors was undertaken on a weekly basis,
Gunite consists of crusher dust, sand and cement. On site
water is added to this dry mixture while being sprayed with
a compressor at +-7 bar. The lateral support to the new office
of the Prime Minister is a permanent gunite wall, i.e. no addi-
tional structure will be constructed in front of it, and it must
support the retained soil over the three-metre spans between
the slabs of the building for the lifetime of the building. These
lateral support walls will require two layers of reinforcing
mesh and gunite with a design strength of 25 MPa.
A Furukawa drill rig drilling 200 mm diameter holes for soil nail installation.
Pictured is a typical section through lateral support wall.
usually on a Friday morning at sunrise before
any operations on site would start.
The lateral support project ran over a
period of 105 days and was completed on
schedule in the middle of May 2015. The
construction of the buildings have however
been put on hold due to the drought the
country is experiencing.
The Stefanutti Stocks Geotechnical site
crew, comprising of South African expats
and a number of local Namibian residents
who have been trained as rockcreter
operators and nozzlemen.