周期性荷载作用下岩石力学特性数值模拟研究

为研究周期性荷载作用下岩石的力学特性,开展了基于离散单元法(DEM)的岩石疲劳数值模拟试验,通过模拟单轴压缩试验研究了数值模型中微观参数对试样宏观参数的影响,再通过数值疲劳试验研究了砂岩的疲劳变形特性。结果表明,砂岩的疲劳应力—应变曲线受控于单轴应力—应变过程曲线,疲劳破坏时的轴向应变即为周期性荷载最大应力在单轴应力—应变曲线中所对应的峰后部分应变。通过分析砂岩的疲劳渐进破坏过程发现,最大应力和平均应力是影响砂岩疲劳寿命的两个重要因素。研究成果对于了解岩体疲劳破坏机理、合理评价工程稳定性有重要意义。

Numerical Study of Mechanical Behavior of Sandstone under Periodic Loading

Discrete Element Method (DEM) is employed to numerically study the mechanical behavior of intact sandstone specimens under periodic loadings. In order to explore the relationship between micro-parameters and macro-parameters, uniaxial compression test on sandstone specimen is performed firstly. To study the fatigue deformation characteristics of sandstones, the numerical fatigue tests are carried out. The results show that the fatigue stress-strain curve of sandstone is controlled by the stress-strain relationship under uniaxial compression condition. The terminal strain of the sandstone at failure is equal to that of post-peak value corresponding to the maximal periodic loading. In addition, the fatigue progressive failure of sandstone is illustrated in this study, and the average and maximum of fatigue load are found to be the most important factors affecting the fatigue lifespan of sandstone. This research is meaningful to understand the fatigue failure mechanism of rocks and rationally assess the stability of engineering projects.