Geotech

Founded in 1903, Roedean (SA) is a prominent all-girls’ school located on the corner of Houghton Drive and Carse O’Gowrie Road in Johannesburg, South Africa.  Damage was experienced at the school during the construction of the Gautrain tunnel between 2007 and 2010. ARQ (Pty) Ltd was requested to carry out the geotechnical investigation and design remedial works for the Astroturf pitch, tennis courts, swimming pool and various associated structures. As poor soil conditions were observed during drilling, this site provided a unique challenge to improve conditions at the site that required very high tolerances with regards to settlement and heave.

From the results of the core drilling and specialised CSW testing, it was determined that Rapid Impact Compaction (RIC) with stone columns would be a cost-effective solution for this site. The RIC machine utilises a weight in the order of 9 tons which is dropped at the rate of 40 blows per minute from a height of 1.0m and is a controlled means of compacting the founding material to an acceptable level. The RIC method can be effective to depths up to 3.0m below natural ground level with little excavation of the in situ material necessary.

Project details