Jones & Wagener designed the lateral support and shaft lining for 6 temporary shaft excavations carried out in the dolomite to facilitate the construction of the pier foundations for Viaduct 5 of the Gautrain in Centurion. The shaft excavations were 7m in diameter and varied in depth between 24m and 36m.

A concrete collar was constructed on surface to provide a stable working platform, to act as a kickplate and a guide for the excavation and lining operations below. The lateral support and lining was a combination of shotcrete, mesh, soil nails, rockbolts and splitsets being applied as necessary to the highly variable soil conditions typically found in dolomite. The shotcrete wall thickness was varied to resist the hoop stress and buckling load resulting from the lateral earth pressure.

A removable steel blasting cover was desinged to prevent flying rock fragments from exiting the shaft during blasting.

Location