Experimental Studies And Theoretic Analysis Of Static & Dynamic Mechanical Characteristics Of Rock Salt.

Systemic experimental investigation and theoretic analysis on the mechanical aspects such as static strength characteristics, creep characteristics and dynamic characteristics on impact for energy (petroleum and gas) storage or wastes (radioactive and toxic wastes) disposal in host rock salt have been conducted in the dissertation.There are two aspects for experimental studies and theoretic analysis of the rock salt: one is static experimental studies and theoretic analysis including uniaxial and triaxial compressing and creep experiments; another is dynamic experimental studies under impact loading. The strain rate of the loading for the experiments is from 10-9s-1(creep experiments), 10-4s-1--10-6s-1(compress experiments)to 10+4s-1--10+6s-1(impact experiments).Firstly, mechanical properties are analyzed to uniaxial and triaxial compress experiments combining the curves of uniaxial complete stress—strain of rock salt; theoretic analysis is conducted and simulated by means of uniaxial damage constitutive model theory combining experimental results; in the meanwhile, triaxial damage constitutive model is also established basis for disturbed conception model of Desai and combining the experimental curves of triaxial complete stress—strain of rock salt, it is simulated to experimental results by utilizing the damage model.Secondly, creep mechanical properties are analyzed to uniaxial and triaxial creep of rock salt; main constitutive equations of rock salt up to now are briefly introduced and discussed; the damage constitutive equation of steady creep rate is recomposed basis on creep results and damage characteristics of rock salt and the constitutive equation of transient creep rate is also established according to visco-elastic-plastic model theory, the results of the constitutive equation of the dissertation are compared with the ones of Hou/Lux model and experimental results, the compared results show that the results of the equation of the dissertation are good agreement with the others; The rate equation of creep mechanism of rock salt is simplified through creep mechanism analysis of solid materials, the map of creep mechanism of rock salt is also set up on data of many former researchers and the creep microstructures of rock salt is studied and analyzed by means of the method of fractal geometry at different high temperatures.Thirdly, the impact dynamic properties of rock salt are studied because of the exploding possibilities for energy underground storage by SWT method which is so called shear wave tracing technique. Two experimental phenomena are discovered for the first time in the impact dynamic experiments, one is that there is another unloading shear wave before the unloading compress wave besides routine four impact waves under the process of compress-shear impact of rock salt; another is that the part damage of the rock salt has been healed because part of the rock salt is melt down and then it would be re-crystallized as high temperature under the process of high speed impact. The constitutive equation and state equation are established according to mechanical properties of impact experiments, stress wave theory and damage theory; models of rock salt under impact are also investigated, at the same time, the process of the impact experiments are simulated by POT code.Some valuable conclusions are reached and should be helpful for further research with regard to energy storage or wastes particularly radioactive and toxic wastes disposal in the host rock salt.