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压应力作用脆性岩石渐进及蠕变失效特性是其力学性质研究的两个主要研究方向。其对于深部地下开挖围岩稳定性的判断有着重要的指导意义。岩石内部微裂纹扩展对脆性岩石的渐进及蠕变特性有着重要的影响。因此,基于岩石的应力与裂纹扩展关系及裂纹扩张演化法则,并结合宏细观损伤定义之间的关系,提出了一个新的宏细观力学模型,推出了岩石完整的应力–应变关系与蠕变理论表达式。分析了围压对岩石的应力–应变关系的影响。研究了岩石内部初始微裂纹尺寸及裂纹间摩擦系数对应力应变关系及岩石强度的影响。并给出了不同围压下岩石裂纹初始应力与峰值应力,其对蠕变实验中的施加应力初始值选取提供了一定参考。然后,研究了恒定围压、轴压分级加载应力路径下的岩石蠕变应变及应变率变化趋势。通过试验结果验证了理论模型的合理性。进而,对压应力作用下细观裂纹扩展对岩石力学特性影响的理解提供了一定的理论参考。
Compressive stress The gradual and creep failure characteristics of brittle rocks are two main research directions of their mechanical properties. It has an important guiding significance for judging the stability of surrounding rock in deep underground excavation. The propagation of microcracks in rock has an important effect on the gradual and creep characteristics of brittle rocks. Therefore, a new macro-mechanics model is proposed based on the relationship between stress and crack propagation and the law of crack growth and evolution and the definition of macro-damage. The complete stress-strain relationship and creep Variable theory expression. The effect of confining pressure on the stress-strain relationship of rock is analyzed. The effect of the initial microcrack size and the friction coefficient between the cracks on the stress-strain relationship and rock strength was studied. The initial stress and peak stress of rock crack under different confining pressure are given, which provide some reference for the initial value of applied stress in creep experiment. Then, the variation trend of creep strain and strain rate of rock under constant confining pressure and axial compressive loading stress path are studied. The test results verify the rationality of the theoretical model. Furthermore, some theoretical references are provided for the understanding of the influence of meso-crack propagation on the mechanical properties of rock under compressive stress.