Determination of the engineering properties of the coode island silts using a self boring pressuremeter : Hughes, J M O; Ervin, M C; Holden, J C Proc 3rd Australia-New Zealand Conference on Geomechanics, Wellington, 12–16 May 1980, V1, P249–254. Publ Wellington: New Zealand Institution of Engineers, 1980

Abstract

The eastern approaches of Melbourne's West Gate Bridge are being constructed as an elevated freeway some 2 km long. For the most part this freeway is being supported on large diameter cast in situ reinforced concrete piles. These piles range in diameter from 1.1 to 1.5 m and are socketed into Silurian mudstone and sandstone. These piles are generally in excess of 40 m in length The upper 30 m to 35 m is in alluvial deposits ranging from dense gravels to soft silty clays. The upper 10 m to 20 m of these deposits are in the so-called Coode Island Silts, which are in fact predominantly soft to firm silty clays. These piles must resist the heavy vertical loads from the dead and live loads of the freeway structures as well as lateral loads imposed by thermal stresses in the bridge deck and substantial construction loads resulting from the prestressing of the deck. The vertical loads are all assumed to be carried in the mudstone. The method of analysis of these pile sockets is described by Williams (1980). The in situ strength and moduli, required for this analysis, have been determined by pressuremeter testing. A significant portion of this testing has been carried out using a high pressure pressuremeter described by Hughes and Ervin (1980).