2024 – Cross-Valley Deformation Behaviour of an Embankment Dam Founded on Extremely Weathered Granodiorite

Ramin Raeesi, Stephen Chia

Understanding the deformation behaviour of dams can provide insight into how and where a failure may occur in the dam. In the case of embankment dams, a potential mechanism of failure is internal erosion through a defect near the dam crest formed by tensile transverse cracking due to cross-valley differential settlement and resulting development of extension strains during and post construction. Cross-valley differential settlement and cracking can be exacerbated if (a) the embankment is founded on a compressible soil foundation, and (b) variations in thickness of the compressible soil foundation. Differential settlement and cracking may be an issue even for relatively shallow height embankments, depending on the compressibility of the foundation and its cross-valley profile. Undertaking cross-valley numerical modelling can be a helpful tool to inform on the potential development of extension strains and transverse cracking in an embankment, particularly when only partial or no deformation records are available. This paper presents a summary of the cross-valley numerical modelling undertaken on Cardinia Reservoir’s Saddle Dam 3, a zoned earthfill embankment founded on extremely weathered granodiorite.