Study On Creep Experiments And Theoretical Model Of Marble Under Cyclic Temperature And Permeable Pressure

With the construction of the western development, the environment of geotechnical engineering is more and more complex, which results in great changes of mechanic properties of the surrounding rockmass and increasing engineering disasters. Large temperature difference by cyclic temperature (annual) makes rockmass generate thermal stress and time-dependent deformation, which results in the periodic expansion and contraction of rock fracture. Aiming at these problems above, a set of creep experiments on marble under cyclic temperature as well as permeable pressure are carried out; the law of time-dependent deformation of marble under cyclic temperature and permeable pressure is mastered; thermo-visco-elastic-plastic creep model of marble under cyclic temperature and permeable pressure is proposed, which is introduced the coupled thermo-hydro-mechanical (THM) theory. Concretely, creep behaviors of marble under cyclic temperature and permeable pressure are simulated by finite element method. In sum, the main work and conclusions including:1. The triaxial creep experiment of marble under different temperature, pore water pressure, axial pressure and confined pressure are carried out, and the variation law of time-dependent axial deformation of marble under different temperature, pore water pressure, axial pressure and confined pressure is analyzed, the creep deformation mechanism of marble under cyclic temperature and permeable pressure is investigated, and the basic laws of effects on triaxial creep of marble by cyclic temperature and permeable pressure are mastered. The experimental results indicate that: the ratio of creep deformation of marble to instantaneous elastic deformation under 90℃constant temperature condition is less than 30℃constant temperature condition, the axial creep deformation of marble increases ladderlikely with the numbers of the cyclic temperature, which suggests that the cyclic temperature makes marble mass damage. Because of the exist of pore water pressure, the ratio of creep deformation of marble to instantaneous elastic deformation is bigger, however, the damage of cyclic temperature to marble is not significantly effected. Because of the increasing of confined pressure, the ratio of creep deformation to instantaneous elastic deformation decreases significantly, but the damage of cyclic temperature to marble increases.2. Base on the law of triaxial creep experiments, the thermo-elastic component and factor of damage caused by cyclic temperature is induced to k-b model, thermo-visco-elastic-plastic creep model of marble under cyclic temperature and permeable pressure is proposed, which is suitable to the experiments, properly reflects the effect of cyclic temperature and permeable pressure to marble creep.3. thermo-visco-elastic-plastic creep model of marble which is proposed above is induced to coupled THM theory, so the coupled THM governing equations about cyclic temperature are proposed, the equivalent weak forms of coupled THM governing equations considing cyclic temperature are obtained by Galerkin method, as well as the calculation formulas of finite element method. Then the calculation program of coupled THM creep about cyclic temperature written in Visual Fortran is developed, the creep progress of marble under cyclic temperature and permeable pressure is simulated. The influence of cyclic temperature and permeable pressure on marble are analyzed.