Experimental Study on the Influence of Temperature on Rock Salt Creep

Constructing salt cavern gas storage in the ultra-deep strata more than 2000 m in depth is an important strategic technologic development in China. A primary issue is that higher temperature affects the creep behaviors of the surrounding rock. In this paper, triaxial creep tests of rock salt under multi-stage temperatures were carried out to study the influence of temperature on the creep behaviors of rock salt. Synchronous acoustic emission monitoring was performed throughout the creep test to study the microcracks characteristics of rock salt during creep at different temperatures. The results show that the duration of transient creep decreases with the increase of temperature. The steady-state creep rate increases with the increase of temperature. Temperature rise prompts the creep of rock salt to enter the volume dilatation stage. By analyzing the acoustic emission energy/counts, it is found that the microcracks generated during the creep at high temperature are few, but there are more at low temperature. Microcracks are generated intensively during rising temperatures. By analyzing the characteristics of the acoustic emission spectrum, it is found that when the temperature is low, the cracks generated are mainly intergranular cracks with a larger size, and they are mainly intragranular cracks with a smaller size when the temperature is high. The research in this paper is helpful to further understand the creep properties of ultra-deep rock salt and provides an important basis for the design, construction, and operation of gas storage salt caverns.

Automated summary

Constructing salt cavern gas storage in the ultra-deep strata of over 2000 m in depth is a crucial strategic development in China. This paper conducted triaxial creep tests and synchronous acoustic emission monitoring on rock salt under multi-stage temperatures to examine the impact of temperature on its creep behavior. The results indicate that higher temperature leads to shorter transient creep duration and a higher steady-state creep rate. Moreover, temperature rise initiates volume dilatation creep and generates more microcracks. This research enhances the understanding of the creep properties of ultra-deep rock salt and provides essential insights for the design, construction, and operation of gas storage salt caverns.