热−水−力耦合条件下黏土岩蠕变特性研究

黏土岩作为放射性核废料处置的备选介质，长期处于热-水-力耦合的复杂条件下。为研究围岩的长期稳定性，开展了一系列不同围压和偏应力下的黏土岩加温-降温排水蠕变试验。得出以下结论：温度的升高会提升黏土岩的蠕变速率，延长衰减蠕变阶段的时间，但是降温过程中试样主要以冷缩变形为主，并未见明显的蠕变变形；围压的降低以及偏应力的增加会提高黏土岩的蠕变速率，并且这种影响会随温度的升高明显加剧。基于试验结果，在Perzyna过应力理论的基础上引入蠕变硬化、蠕变损伤以及热损伤，建立了黏土岩热-水-力耦合蠕变模型。通过ABAQUS软件及其子程序对该模型进行数值实现，模拟结果与试验结果的对比初步表明该模型可以很好地描述热-水-力耦合条件下黏土岩的蠕变特性。

Study on creep characteristics of claystone under thermo-hydro-mechanical coupling

As an alternative medium for the underground disposal of radioactive waste, claystone will be in the complex conditions of thermo-hydro-mechanical coupling for a long time. In order to study the long-term stability of surrounding rocks, a series of heating-cooling drainage creep tests on claystone was carried out under different confining pressures and deviatoric stresses, and the following conclusions were drawn. The rise of temperature will increase the creep rate of claystone, and extend the time of decay creep stage. But during the cooling process, the samples mainly experience shrinkage deformation without obvious creep deformation being observed. The decrease of confining pressure and the increase of deviatoric stress will increase the creep rate of claystone, and this effect will be significantly aggravated with the increase of temperature. Based on the experimental results, creep hardening, creep damage and thermal damage were introduced on the basis of Perzyna overstress theory, and a coupled thermo-hydro-mechanical creep model for claystone was established. The model was numerically implemented by ABAQUS and its subroutines. The comparison between the simulation results and test results demonstrates that the model can effectively describe the creep characteristics of claystone under thermo-hydro-mechanical coupling.