Design and performance of cast in situ piles in extensively jointed silurian mudstone : Williams, A F; Ervin, M C Proc 3rd Australia-New Zealand Conference on Geomechanics, Wellington, 12–16 May 1980, V1, P115–121. Publ Wellington: New Zealand Institution of Engineers, 1980

Abstract

Reasonable methods exist for the design of piles socketed into rock which is massive or which has only a few tight joints, however, difficulties arise when the rock is extensively jointed. Such difficulties were experienced during the construction of Melbourne's eastern freeway, which required twin bridges to be constructed over the Yarra river in an area known as the studley park fault zone, where the silurian sedimentary rocks have undergone severe folding, faulting and fracturing. The joints in the area were found to be slickensided, generally with thin clay coatings and with joint frequencies of 10 to 100 joints/m. In order to confirm the practicability of economically constructing sockets in the faulted rock and in order to develop a design method, two test sockets were constructed. An end bearing test was carried out in one and a side resistance test was carried out in the other. During the subsequent bridge construction, eight of the service piles were proof loaded to reduce the expected high first loading settlements. The work was supported by detailed geological logging of n size core and the rock sockets, triaxial tests on intact samples of rock, and pressuremeter tests. The results of the pile tests and the pressuremeter tests have been related usefully to joint frequency (a).