The site of the Kowyn's Pass shelter is situated on the road traversing the escarpment between Graskop and Bosbokrand in the north-eastern Transvaal. The area was subject to a major fall of rock in 1973. Further falls, however, continued after the suspect area was anchored. The Transvaal Provincial Roads Authority decided towards the end of 1977 to construct a reinforced concrete rockfall shelter as a permanent and fail-safe protective measure. The design of the structure, of which construction was completed in August 1980, is discussed in the paper. A brief review of the state of the art of designing rockfall shelters against impactive loading is also presented.
Die terrein van die Kowynspas skuiling is op die pad oor die platorand tussen Graskop en Bosbokrand in die noord-oos Transvaal. 'n Groot rotsstorting het in 1973 voorgekom. Verdere stortings het egter steeds voorgekom nadat die verdagte gebied met ankers bevestig is. Die Transvaalse Provinsiale Paaie Administrasie het teen die einde van 1977 besluit om 'n gewapende beton rotsskuiling as 'n permanente en heeltemal veilige maatreel op te rig. Die ontwerp van die struktuur, wat in Augustus 1980 voltooi is, word in die verhandeling uiteengesit. 'n Kort oorsig word ook gegee van die ontwikkelingstand ten opsigte van die ontwerp van rotsskuilings vir 'n impaktiewe belastingstoestand.
As a result of the tremendous variation of the properties of ferricretes found in the south-western Cape, especially with regard to their uses for road building, it was decided to conduct an in-depth investigation to establish the reasons and extent of this variation in formation. The investigation was conducted on the in situ material in two borrowpits located in a road contract, as also on the ferricrete in the road pavement extracted from these two sources. All the tests discussed were conducted in the normal site laboratory.
The discussion contained herein reviews the origin of ferricrete, the results of the tests conducted and some recommendations as to extraction and construction procedures. The tests conducted on the in situ ferricrete deposits included such aspects as the California Bearing Ratio, the Atterberg Limits, moisture contents, stabilization and the reaction of certain primes.