中文摘要：

以北山花岗岩为研究对象,采用MTS815岩石力学试验系统开展不同温度条件下的蠕变特性试验研究。考虑温度对花岗岩特征参数的影响,结合岩石蠕变破坏过程中的损伤演化规律,提出了一种新的高温损伤流变元件。通过将高温损伤流变元件代替经典西原模型中Newton元件的方法,构建了能够描述不同温度条件下花岗岩蠕变全过程的本构模型。分析了不同温度条件下花岗岩单轴蠕变试验结果,确定了模型参数,获得了温度对花岗岩蠕变关键参数的影响规律。通过对花岗岩高温蠕变模型进行参数敏感性分析,揭示了弹性模量、黏性系数等关键参数对花岗岩蠕变特性的影响规律,并验证模型在不考虑温度及损伤的影响条件下可退化为经典西原模型。研究表明,建立的花岗岩高温蠕变本构模型可以准确地描述花岗岩典型蠕变全过程的3个阶段,尤其是加速蠕变阶段。黏性系数受损伤的影响越大,花岗岩的稳定蠕变阶段越短,越容易发生加速蠕变。

英文摘要：

Creep properties of Beishan granite under temperature effect are investigated by using the MTS815 rock mechanics test system. A rheological element with thermo-damage coupling effects is proposed by considering the temperature effect coupled with the damage evolution during the whole creep stage. By replacing the Newtonian dashpot in the classical Nishihara model of the coupled thermo-damage element, a new creep constitutive model for full creep process under different temperatures is set up. Based on a series of creep tests carried out at different temperatures under uniaxial loading condition, the parameters of the creep constitutive model and the variation laws of them along with temperature are determined by fitting to the experimental results of the time-dependent deformation of Beishan granite. A sensitivity study for the analytic solution of the creep model with thermo-damage effect is carried out, showing the effects of creep parameters （including elastic modulus, viscosity coefficient etc.） on a creep strain of granite. In addition, a simplified formula of the creep constitutive relation in the case of no temperature variation and damage influence is given. It is shown that the new creep constitutive model can be simplified to the Nishihara model in the absence of temperature and damage effects. Comparison between the predictive results and experimental data,it is shown that the creep model proposed is capable to provide a precise description of full creep process in granite. In particular, the accelerated process is also well reproduced by the proposed model. A bigger exponent？in the viscosity coefficient leads to a shorter steady-state creep process and earlier onset of the tertiary process.