Engineers Australia

A hundred piles in highly variable ground conditions – pile design for Crown Sydney Hotel Resort

Douglas Warne

Abstract

The new Crown Sydney Hotel Resort development (under construction) at Barangaroo will be one of Sydney’s tallest and most iconic buildings. The project will transform a former container wharf into a 270m tall six-star luxury hotel tower with podium structure and three-level basement. To support this large structure, a combination of diaphragm walls, barrettes and piles were employed. This paper focuses on the design methodology adopted for the pile foundations. A particular methodical design process has also been developed to incorporate this design methodology into an in-house spread sheet to provide rapid responses to changes occurring with pile design during construction.

The development is located at a site that has undergone significant alteration in the past century. Earlier use of the site as finger wharfs and later conversion to a container wharf has seen the site backfilled with highly variable fill material such as slag, concrete and steel mixed in with sandy and clayey soils. The marine influenced erosional environment has led to sandstone cliffs across the site, resulting in rock levels that vary significantly over short distances across the site. Furthermore, the Pittman LIV dyke runs across the site, adding further complexity to the site geology. In addition to the complex site geology, tight settlement and deflection criterion were also imposed on the piles to meet serviceability requirements. These constraints coupled with the large number of heavily-loaded piles (up to about 50MN) necessitated a robust pile design approach which could be adapted to any design change. To calculate settlement of rock socketed piles, the Rowe and Armitage method is a well-accepted method. However, due to the large number of piles and numerous changes in pile loadings, it was not preferred in this case due to the time taken for calculation and there was a need to develop an efficient method. Therefore, the analytical Carter and Kulhawy method was adopted to make the process quicker. This method was also checked against Rowe and Armitage and also checked against numerical modelling. An in-house spread sheet was also developed to streamline this process. The information for pile design was also integrated to a Building Information Management System (BIM) to check against clashes.