Elastoplastic analytical solutions for compressed air energy storage caverns under cyclic loading and unloading and non-hydrostatic in-situ stress

Journal of Energy Storage, vol. 181, pp. 124439

Abstract

Compressed air energy storage (CAES) in hard-rock caverns involves excavation, support installation, first charging, and long-term cyclic charging and discharging. These engineering stages produce different elastoplastic mechanisms, especially under non-hydrostatic in-situ stress. A semi-analytical formulation is developed for a circular cavern under biaxial far-field stress. The solution distinguishes unloading-stage plasticity, an intermediate elastic state, and loading-stage plasticity, and derives the corresponding stress and displacement fields by combining the Kolosov–Muskhelishvili complex-variable elastic solution, the Mohr–Coulomb criterion, radial plastic equilibrium, and non-associated flow. Continuity of radial stress and displacement is enforced at the elastic–plastic (EP) interface, allowing excavation and pressurisation to be treated within one path-dependent formulation. The results show that the lateral pressure coefficient governs both plastic-zone extent and the direction in which yielding and deformation concentrate. Comparison between the loading-side Mohr–Coulomb shear threshold and the tensile cut-off pressure gives failure-initiation pressure envelopes for different confinement and strength conditions. A cyclic damage calculation is then used to estimate progressive degradation, residual displacement, and the maximum allowable operating pressure that considers accumulated damage during long-term operation.

Authors 4

1. Gengyun Liu corresponding

   Ningbo University

   Affiliation as printed

   Institute of Rock Mechanics, Ningbo Key Laboratory of Energy Geostructure, Ningbo University, Ningbo, Zhejiang 315211, China

2. Caichu Xia

   Ningbo University

   Affiliation as printed

   Institute of Rock Mechanics, Ningbo Key Laboratory of Energy Geostructure, Ningbo University, Ningbo, Zhejiang 315211, China

3. Yang Dong

   TU Bergakademie Freiberg

   Affiliation as printed

   Institute of Geotechnics, Technische Universität Bergakademie Freiberg, Freiberg, Germany

4. Azzam Rafig Aachen Department of Engineering Geology and Hydrogeology

   RWTH Aachen University

   Affiliation as printed

   Department of Engineering Geology and Hydrogeology, RWTH Aachen University, Lochnerstr. 4–20 Haus A, D-52064 Aachen, Germany