2023 – Simulation of Collapse Settlement in Rockfill Dams Due to Initial Saturation

Qian Gu, Joshua Chan

During the first filling of rockfill dams, higher settlements commonly occur in the upstream rockfill shoulder due to collapse behaviour. Such displacements cannot be readily considered in numerical simulation due to the lack of specifically developed constitutive models for such behaviour in commercial software packages. This paper presents a simulation of collapse behaviour with a widely used creep model available in Plaxis software. The fundamentals of saturation collapse and time-dependent creep in rockfills are considered similar, with both linked to the breakage of particles due to cracks developing, resulting in a drop of the yield surfaces. In this study, the model parameters were obtained from monitoring data of an existing 85 m- high rockfill dam. The validity of the methodology was also evaluated by comparing typical oedometer and triaxial collapse test results from real rockfill materials. The numerical simulation of the embankment deformation indicates the importance of capturing rockfill collapse upon saturation in obtaining better agreement with the monitoring data.

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