2011 – Hinze Dam Stage 3 Foundation Curtain Grouting

Rob Campbell, Tom Kolbe, Ron Fleming, Christopher Dann

Hinze Dam is an Extreme hazard category water supply dam situated in the Queensland Gold Coast hinterland, owned and operated by Seqwater (formerly owned by Gold Coast City Council). The Hinze Dam Stage 3 works involved raising the previously 65m high central core earth and rockfill embankment approximately 15m to a maximum height of approximately 80m.

The Stage 3 works included a program of foundation curtain grouting, consisting of six discrete grout panels, five of those beneath areas where the embankment was extended and one beneath part of the spillway enhancement works. Five of the six grout panels were essentially single row panels, with one or more partial rows added in specific areas of high grout take. The remaining grout panel (Panel 4) was constructed as a triple row panel.

A number of challenges were encountered and overcome during the Stage 3 foundation grouting works due to highly variable foundation conditions, ranging from extremely low strength residual soil to highly fractured and permeable high strength rock.

The grouting works were undertaken using downstage grouting techniques, with manual recording of data, manual control of grout pressures and injection rates and use of predominantly neat cement grout mixes.

A key issue in the execution of the foundation grouting works was the maximum grout pressures applied to the foundation and this was discussed in detail between the project design team and external review panel. This paper presents the results from project specific grout trials and production grouting to demonstrate that closure of the foundation was consistently achieved (with one exception discussed herein), which supports the grouting approach employed and the adopted grout pressures.

This paper presents a case study description of the Stage 3 foundation curtain grouting works, including a summary of key learnings which may be of benefit to future dam foundation curtain grouting projects.

 

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