Storage of Heated Water in Underground Openings

Abstract

A study is carried out of the anticipated effects on the rock surrounding a storage cavern due to the storage of water at elevated temperatures. Properties of granite and andesite at temperatures between 15 ° C and 100 ° C determined in laboratory experiments are then measured. The rock properties are compressive strength, tensile strength, tangential Young's modulus, Poisson's ratio, coefficient of thermal expansion, and thermal diffusivity. Results are determined for rock specimens prepared in both a dry and a wet condition. In general, the rock properties are adversely affected by moisture and by an increase in temperature. The effect of an increase in temperature is more significant in the wet‐rock specimens. The experimental rock properties determined were used in a numerical analysis to determine the effect of the storage of heated water at a temperature of 100 ° C in a 10‐m‐diameter circular underground opening at a depth of 100 m below the ground surface. For the conditions analyzed, the results indicated that rock surrounding the opening would not be overstressed.