Abstract

The objective of this study is to determine effects of loading rate on compressive strength and deformability of the Maha Sarakham salt under elevated temperatures. The effort is aimed at determining the safe maximum withdrawal rates for the compressed-air energy storage (CAES) in salt caverns. The constant axial stress rates range from 0.0001 to 0.1 MPa/s. The testing temperatures are maintained constant between 273and 373 Kelvin. The results indicate that the shear stress-strain curves monitored under various loading rates and temperatures show nonlinear relations, particularly under high temperatures. To incorporate the thermal and rate (time-dependent) effects into a strength criterion the distortional strain energy at dilation of the salt is calculated as a function of the mean strain energy density. Finite difference analyses (FLAC 4.0) are also performed to determine the stresses and strains at the boundaries of CAES caverns for various reduction rates of the internal pressures. The maximum stresses and strains obtained during retrieval period are used to calculate the strain energy density induced at the cavern boundaries. The results are compared against the criteria developed above, and hence the safe maximum withdrawal rate of the compressed-air can be determined.

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