中文摘要：

基于红砂岩单轴分级加载蠕变试验，结合对试验数据的整理与分析，研究红砂岩蠕变特性，探讨岩石分级加载过程中的硬化-损伤机制。研究结果表明：低应力水平阶段，瞬时变形模量逐级增大，红砂岩出现硬化现象，瞬时应变由0．0372％减小到0．0307％，岩石力学性质以硬化为主；中等应力水平阶段，硬化效应增强的同时损伤也在发展，硬化和损伤相互竞争，不断发展；高应力水平阶段，粘滞系数减小，导致损伤扩散速率增大，蠕变应变由0．013％增加到0．0218％，岩石的力学性质以损伤软化为主。以此为基础，在广义Kelvin模型中引入硬化函数和损伤变量，建立能反映红砂岩硬化-损伤机制的模型，并与红砂岩的试验曲线进行拟合，两者吻合较好。

英文摘要：

Based on the data analysis of the uniaxial step loading creep test of red sandstone, this paper studied the creep property of red sandstone and probed the rock hardening and damage mechanism in the process of step loading. The results show that at low stress level stage, the transient deformation modulus increases with stress levels and the transcient strain reduces from 0. 037 2 % to 0. 030 7 %, causing the red sandstone＇s hardening, which is the dominant rock mechanical property of this period. At moderate stress level stage, damage develops with the reinforcement of hardening effect and both of hardening and damage keep developing while competing with each other. At high stress level stage, the decrease of viscous coefficient leads to an increased damage diffusion rate, and with the creep strain increasing from 0. 013% to 0. 021 8%, damage softening becomes the dominant mechanical behavior. A model was then established by introducing the hardening function and damage variable into the generalized Kelvin model to describe the hardening-damage mechanism of red sandstone. After comparing the model results with the curve of red sandstone tests, it is found that they are perfectly fitted.