Numerical Analysis of a Top-Down Constructed Deep Basement with Diaphragm Walls in Barangaroo, Sydney - A Case Study

Ali Parsa-Pajouh, Brad Azari, Sam Mirlatifi, Henk Buys, Ian Cullen

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Crown Sydney Hotel Resort, is located at Barangaroo South alongside Sydney Harbor on the western side of Sydney’s business district. This building is being developed as a single mixed-use high-rise tower of 72 stories, rising over a multi-level podium and a 3-level basement car park. The tower basement is a 13 m deep excavation with irregular geometry made using top-down construction in highly variable ground and bedrock profiles. The excavation has been retained by the construction of 33 diaphragm wall panels, which resist and transfer the out-of-balance soil and water loads to the 36 internal barrettes by means of multiple levels of slab diaphragms.

2D and 3D numerical methods have been adopted to simulate the complex interaction between the soil and the basement of this structure. The 3D model has been used to capture the 3D effects of the deep excavation and asymmetric wall geometry, including soil pressure changes at the corner panels, potential arching, out-of-balance soil loads, and group effects. A detailed instrumentation and monitoring plan have been developed to assess the performance of the basement during construction. This paper presents the design methodology and the numerical modeling adopted to carry out a robust geotechnical design and successful modeling of the soil-structure interaction. It explains how the numerical model has been validated and calibrated. The numerical predictions are compared with the data that has been collected from the web-based, real-time instrumentation and monitoring during the construction phase. The approaches that have been used to mitigate the associated risks with the design are also discussed in this paper.


Diaphragm wall, deep excavation, top-down construction, numerical analysis, 3D effect, corner effect, instrumentation, monitoring, tall buildings


Parsa-Pajouh, A., Azari, B., Mirlatifi, S., Buys, H., Cullen, I. (2021). Numerical Analysis of a Top-Down Constructed Deep Basement with Diaphragm Walls in Barangaroo, Sydney - A Case Study, Vol. 7, Issue 1, p.95-112. doi: 10.4417/IJGCH-07-01-05


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