Experimental Research On Mechanical Characteristics Of Rock Salt Under Coupling Between Stress And Temperature

Due to the characteristics of low porosity and permeability, self-injury recoveryand large plastic deformation; Rock salt is considered as an ideal place to store oil,natural gas and high-level radioactive waste. Our country is abundant in rock salt whichis widely distributed, allowing for the massive construction of underground petroleumstorage caverns. According to the feather of the ultra-deep formation, large amounts ofsystematic mechanical tests in high temperature and high pressure have been conductedfor Qianjiang rock salt underground gas storage. The main contents are as follows:By means of uniaxial and triaxial compression tests on rock salt at normaltemperature and different high temperatures, the feature of deformation and short termstrength with the stress-temperature coupling are studied. Based on the uniaxial andtriaxial stress-strain curves at different high temperatures and normal temperature, thepeak stress, yield stress and elasticity modulus of rock salt change with the temperatureare deeply discussed. The results show the initial yield surface of rock salt and thefailure modes are also analysized.Theoretical methods and empirical methods from two aspects are used tosummarize the theory of creep of rock salt. Numerous constitutive equations of transientcreep and steady state creep which describe the temperature effects of rock salt areshowed. Adopting the dislocation theory, the creep mechanism of rock salt is analysizedon a micro level, can be divided into four categories: glide, cross slip climb with glide,dynamic recrystallization.By means of creep tests on rock salt at different high temperatures, pressures anddeviatoric stresses, the feature of creep deformation and long term strength with thestress-temperature coupling are studied. Based on the creep curves at different hightemperatures and deviatoric stresses, the effects of temperature and deviatoric stresseson steady-state creep rate of rock salt are deeply discussed. Finally, the relatedconstitutive equation of steady-state creep of rock salt is given.