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ORIGINAL PAPER

Investigation on the Deformation and Strength Characteristics of Rock Salt Under Different Confining Pressures Wei Liu . Xiong Zhang . Haoran Li . Jie Chen

Received: 31 January 2020 / Accepted: 23 May 2020 Ó Springer Nature Switzerland AG 2020

Abstract The deformation and strength characteristics of rock salt is significant for the safety of hydrocarbon energy (oil, gas) storage in salt caverns. To overcome the problem of determining the peak strength by simultaneously considering the dilatancy characteristics of salt rock, compression experiments were carried out on Pingdingshan salt rock under different confining pressures. The results shew that the uniaxial experiment of salt rock presented a brittle failure, but the presence of impurities improved the strength of samples. After the confining stress reached a ‘‘Transition confining pressure’’—6.55 MPa, which was determined by using a chart method, the strength of salt rock increased greatly and behaved a strong strain hardening phenomenon. An empirical method to determine the ‘‘transition confining pressure’’ was put forward, and it was also suggested that the minimum operating pressure in a gas storage salt cavern should be higher than this value. The experiments under different confining pressures indicated that the higher the confining pressure was, the more hysteretic the

W. Liu  X. Zhang  J. Chen (&) State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China e-mail: [email protected] H. Li (&) School of Civil Engineering, University of Shijiazhuang Tiedao, Shijiazhuang 500043, Hebei, China e-mail: [email protected]

dilatancy occurred. Based on this result, a method to determine the peak strength of salt rock based on a certain axial strain value (6%) or the initial point of dilatancy was proposed. Then the peak strength of the salt rock samples in this study was calculated to verify the feasibility of this method. This study provided the determination methods for the ‘‘transition confining pressure’’ and the peak strength for salt rock, which was a reference for the evaluation and operation of the gas storage salt caverns. Keywords Gas storage salt cavern  Salt rock  Confining pressure  Peak strength  Axial strain  Dilatancy

1 Introduction Reducing the carbon emission and increasing the use of clear energies are significant for China (Liu et al. 2013; Qiao and Yang 2020; Chang et al. 2003; Fan et al. 2020a, b). In recent years, China has largely increased the use of clean energy, such as natural gas (Zhang et al. 2020a), wind and solar power (Qiao and Yang 2020; Zhang and He 2013). As a transition between traditional fossil fuel and renewable energy, natural gas, will play an important role in the lowcarbon era of China for the long term. In recent years, the annual consumption of natural gas has increased to 8% (Dong et al. 2017), and it is expected the

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Geotech Geol Eng

proportion of natural gas in the nation’s energy