Through a serial of rock salt uniaxial compression meso-mechanics experiments considering coupled stress-dissolving effect, the differences of mechanical properties of rock salt with/without the dissolving effect have been explored. Based on the result of experiments, the rule that mechanical property of rock salt has been changed under the dissolving effect has been proved; the mechanism of variation of mechanical property of rock salt on dissolving effect is that the critical stress intensity factor of crack of rock salt has been decreased; the relationship between axial stress and dissolving time on dissolving phase, under the condition of different situation of cracks of rock salt specimen, has been analyzed; the variation of mechanical properties on rock salt with dissolving effect can be described quantitatively with the expression between H and dissolving mass m, H is the ratio of the axial stress value before and after dissolving. The achieved results on this paper can provide a foundation for the further analyses of coupled stress-dissolving mechanism of rock salt.
Low permeability rock stratum, such as rock salt and granite, and mushy rock stratum are been using for underground energy storage. Because of very low permeability (values are generally less than 10-20m2), well-known creep characteristics, and property of being dissolved by water easily (which makes excavation of rock salt cavern easier and more economical) of rock salt, most of energy storage vault has been building in rock salt stratum or abandoned salt mine.
During the operation period of underground rock salt storage vault, interaction between mechanical property and dissolved characteristics of rock salt has been existed: on the one hand, because of stress or variation of stress, as the adjacent rock, plastic deformation of rock salt has been happened, and then different size of crack has been produced. When contact with water solution, because cracks have been produced and expanded constantly, contact area between rock salt and water has been increased, and then dissolving rate of rock salt has been accelerated; on the other hand, because of dissolving effect, rock salt crack has been dissolved in water solution, jaw opening of crack has been further increased, and mechanical property of rock salt and stress field of the adjacent rock has been changed. In a word, properties of rock salt being confined in above process mainly include: mechanical properties, dissolved characteristics, permeability, coupled fluid-solid effect, analysis of stability and shape of rock salt cavern.
A lot of scholars researched properties of rock salt, and obtained a wealth of research results. Udo Hunsche et al [1, 2] has researched the true triaxial strength tests on rock salt and mechanical properties of rock salt as the host rock material for a radioactive waste repository. Ahmad Pouya [3] has studied the micro-macro mechanical properties of rock salt. Chan, K.S. et al [4] has researched creep fracture of rock salt. Zhou Shiguang et al [5-7] has researched short-term intensity and deformation properties of rock salt.
