Time-dependent degradation mechanisms and instability prediction of dangerous rock mass on reservoir banks under multiphase hydro-mechanical coupling effects

Abstract

Time-dependent assessment of dynamic instability, rockburst phenomena, and potential collapse of unstable rocky reservoir banks presents the critical engineering challenges under multiphase hydro-mechanical coupling effects. While existing research has primarily focused on reservoir bank instability under static water level conditions, it has largely overlooked the process of time-dependent material degradation in stability assessment frameworks. This study addresses this knowledge gap through an integrated approach combining numerical modeling and experimental investigation. A finite element model was developed based on the Jianchuandong Rock Mass (JRM), incorporating hydrostatic pressure variations and strength reduction techniques. Com- plemented by controlled dry-wet cycling experiments simulating reservoir water fluctuations, the research quantitatively evaluates the coupled effects of hydraulic variations and progressive rock deterioration. The re- sults reveal significant temporal coupling between water level fluctuations and rock mass degradation, which mutually accelerates the destabilization process and ultimately leads to instability in the fifth hydrological year. The findings demonstrate that the proposed framework effectively captures the hydro-mechanical coupling mechanisms underlying reservoir bank behavior. This multi-field coupled analysis methodology achieves marked advancements beyond traditional static approaches through explicit consideration of time-dependent geotech- nical mass deterioration characteristics, providing technical support for the lifecycle assessment of long-term operation water conservancy projects.

Keywords

Hydraulic-mechanical coupling / Rocky reservoir banks / Time-dependent degradation / Instability prediction / Fluctuation of reservoir water

CRediT authorship contribution statement

Yanchang Jia: Investigation. Zhihao Chen: Data curation. Tong Jiang: Validation. Luqi Wang: Supervision. Wang Lu: Writing - orig- inal draft. Kaiqiang Zhang: Software. Zhihua Zhang: Validation. Dongdong Li: Formal analysis.

Declaration of competing interest

All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the National Key R&D Program of China (No. 2024YFC3211204), the Postgraduate Innovation Capacity Enhancement Project (No. NCWUYC-202416024) at North China Uni- versity of Water Resources and Electric Power, Open Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety of China (No. SKLGME023002), and China Postdoctoral Foundation (No. 2024M753842).

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