ABSTRACT

In this paper, we present geomechanical stability analyses for underground rock caverns, subjected to a high inner storage pressure inside the caverns. We first present development and application of a simple mathematical solution for analyzing ground uplift associated with underground rock caverns pressurized by internal compressed air or natural gas storage, and investigation of the effect of design parameters of underground storage caverns on the safety against ground uplift. The results of parametric sensitivity analysis including storage pressure, cavern size, overburden depth, in-situ stress state, and rock physical properties such as cohesion and friction angle are presented. Therafter, we present an investigation about the potential impact of permeability change in concrete linings as a results of local straining and potential fracturing using numerical modeling of coupled non-isothermal, multi-phase fluid flow and geomechanical processes around underground storage caverns. Our modelingresults showunder what conditions the pressurization of cavern could lead to tensile failure and localized air leakage. From these resutls, we conclude that our global ground uplift analysis can provide useful information in site selection and preliminary design stage, and the local fracturing investigation using a coupled simulator may be useful in establishing detail design and optimal operation strategy of pressurized underground rock storage caverns.

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