2023 – Rookwood Weir – Data Collation And 3D Modelling On The Fitzroy River, Queensland.

Isabella Foldvary, Chris Chamberlain, Graham Irvine

Construction of Rookwood Weir, located in central QLD, commenced in April 2021 and is anticipated to be complete by the end of 2023. For the construction stage, a three-dimensional (3D) model was developed to refine pre-existing geological models and include construction stage data. The underlying methodology incorporates construction stage foundation mapping, geotechnical investigation data, information from daily drone flights and selected construction data.

This approach was also used during the construction of Cotter Dam, built between 2009 and 2013, and more recently on multiple dam projects prior to refinement at Rookwood Weir. Technological advancements have since allowed the workflow of hand drawn foundation mapping to progress into a 3D space.

The Rookwood Weir Project (RWP) 3D model has been successful in:
• Providing up to date information to the construction team and design team regarding the foundation conditions as the foundation works progress,
• Creating an as-built model of foundation conditions to inform interim and future reporting as the construction progresses,
• Updating the broader foundation ground model with information from (for example) foundation mapping, foundation grouting program or the Cut-off Wall.

By importing various types of data into one model, several aspects of the project can be visualised and manipulated where necessary. On completion of the weir, the model will be provided to the weir owner and can be used (for example) to reduce the need for new ground investigations associated with future safety reviews or risk assessments.

The 3D model has incorporated technical elements as outlined by (1) Guidelines For Geotechnical Investigations Of Dams, Their Foundations, and Appurtenant Structures (ANCOLD, 2020), (2) Australian Standard – Geotechnical Site Investigations (AS1726, 2017) and (3) Guidelines For The Development And Application Of Engineering Geological Models On Projects (IAEG, 2022).

This paper provides an example of how 3D modelling can be successfully implemented during a project’s construction stage and emphasises the importance of updating the geological model through the project lifecycle.

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