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为研究三向应力状态下周期荷载对工程岩体长期稳定性的影响,对黄砂岩试样进行了不同围压的常规三轴压缩试验和周期轴向荷载疲劳试验,得到了黄砂岩疲劳破坏的轴向、环向及体积变形特性。试验结果表明:常规三轴轴向周期荷载作用下,黄砂岩疲劳破坏的轴向、环向以及体积变形受到静态应力-应变曲线变形量的控制;疲劳破坏轴向、环向的峰值变形和不可逆变形均符合三阶段倒S型曲线发展演化规律;围压对轴向变形发展规律有一定强化作用,对环向变形发展规律却有所抑制;在疲劳破坏变形过程中,峰值应变ε_(max)具有和不可逆应变ε~p相似的发展规律,弹性应变ε~e在3个阶段基本保持不变,不可逆应变增量Dep的变化规律能够反映3个阶段应变速率的发展演化规律;变形比强度更适合作为岩石疲劳破坏的依据,黄砂岩的疲劳破坏变形特性研究为建立岩石的疲劳破坏力学模型做了基础。
In order to study the effect of cyclic loading on the long-term stability of engineering rock mass under three-dimensional stress conditions, the conventional triaxial compression tests and cyclic axial load fatigue tests of yellow sandstone samples under different confining pressures were carried out, and the fatigue failure of yellow sandstone Axial, circumferential and volume deformation characteristics. The experimental results show that the axial, circumferential and volumetric deformations of the yellow sandstone under cyclic loading are controlled by the deformation of the static stress-strain curve under normal triaxial axial cyclic loading. The failure of the axial, circumferential peak deformation and irreversible The deformation is in accordance with the development and evolution of the three-stage inverted S-curve. The confining pressure has a certain strengthening effect on the axial deformation and restrains the development of the circumferential deformation. During the process of fatigue failure, the peak strain ε max, Has similar development rules with irreversible strain ε ~ p. The elastic strain ε ~ e remains unchanged in three stages, and the variation of irreversible strain increment Dep can reflect the evolution law of strain rate in three stages. The deformation strength Suitable as a basis for fatigue failure of rock, the research on the fatigue failure and deformation characteristics of the yellow sandstone provides the basis for establishing the mechanical model of fatigue failure of rock.