An Improved Dilatancy Boundary for Salt Rock

Abstract

Salt layers and domes have been used to store hydrocarbons and to dispose of nuclear wastes. One of the most important properties of rock salt is its good deformability, which can neutralize the deviatoric stress and heal damage. Structural stability is one crucial requirement in salt cavern design and construction. Various criteria and methods have been proposed for salt cavern design and stability analysis. This paper investigated the advantages and limitations of various stability criteria. The results suggest that the stability criterion proposed by De Vries et al. is the most suitable approach for stability analysis. However, the effects of the stress path and history are not considered in this criterion. To overcome this shortcoming and to integrate effects of the stress path and history within the criterion, an updatable dilatancy criterion is proposed. In the proposed dilatancy criterion, a representative parameter is defined based on the healing and damage that occurred in a previous cycle of loading and unloading, which takes into account the stress path and history and their effects on the behavior of rock salt in subsequent cycles. The new criterion gives deeper insight into the strength of rock salt based on previous damage-healing background, and is useful in appropriate design and operation of salt cavern.