Experiment Research On The Effects Of Temperature And Viscoelastoplastic Analysis Of Beishan Granite

Much importance was attached on the disposal of nuclear waste in the world. A considerable amount of research were carried on the mechanical behavior of granite abject to the effects of temperature, which is characteristic of low ductility high density and high intensity and other features suitable for the storage of nuclear waste , oil and gas. While many valuable researches were performed in china and BeiShan district of Ganshu province was determined to be the place for the nuclear waste informally. In this paper, granite of BeiShan was chosen, experiment was made to research on the granite behavior in the effects of temperature , combining damage mechanics and viscoelastoplastic theory, tentative efforts were made in the coupling of thermal and stress as well as rheologic constitutive formula.First, the basic mechanical capability and creep were proceeded on the material test system with the modified three point bending creep fracture test. The modulus and fracture toughness and tensile strength was attained and creep curve in 200 temperature was also presented.Applying basic damage mechanical theory, thermal damage analyseswere performed induced in fracture toughness and modulus, the practicalformula of damage factors varying with temperature and time was given.Damage law of granite specimen were studied, damage factors coupling oftime and temperature was presentedWith the help of coupled damage factor of time and temperature, combining with Nishihara rheological model, elastic and viscopelastic model were modified into a new rheological model considering the effects of timeand temperture.Applying viscoelastoplastic theory, the modified Nishihara model was extended into three dimension, the yield criterion and flow vectors fitting for computing were attained. According finite element theory, the computing method and step of Nishihara rheological model was given, numerical simulating of Three point bending creep test was performed and the results were coincided with that of test.