巴东组紫红色泥质粉砂岩损伤特性三轴试验研究
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摘要: 以宜昌至巴东高速公路中典型的巴东组紫红色泥质粉砂岩为对象，对其进行三轴压缩试验。通过对三轴应力-应变全过程分析表明：岩石破坏的实质是原生节理裂隙的不断扩展、累积、劣化的过程，其应力应变过程可分为线性弹性段，屈服段，应变软化段以及塑性流动四个阶段。基于试验结果探讨了泥质粉砂岩的初始损伤特性，分析结果表明：泥质粉砂岩的初始损伤时的主应力差对数与围压呈线性关系。同时，假定岩石微元强度服从 Weibull 随机分布的特点，合理推导了岩石微元强度的参量，建立了反映岩石破裂全过程的损伤软化本构模型，并分析了基于Weibull 分布的损伤变量与主应力差的抛物线数学关系，并结合试验数据与模型数据进行对比，分析了该损伤软化本构模型是合理的。Abstract: This paper presents the triaxial test results of purple argillaceous siltstone of the Badong formation, which is encountered in the Yichang to Badong Highway. It is found based on the study of stress-strain full procedure curves that the essence of the destruction of the strength of rock is the continual emergency, expansion, accumulation and degradation of native joints. The characteristics of the initial damage are discussed in this paper and the results show that there is a liner relationship between the logarithmic of principal stress difference and the confining pressure. The infinitesimal strength of rock is assumed to obey the Weibull random distribution. The parameter of the infinitesimal strength of rock is reasonably derived and the constitutive model of damage and softening which reflect the whole process of rock failure is established. The parabolic mathematical relationship between the damage variable and the principal stress difference is also analyzed based on the Weibull random distribution. Finally, a conclusion is drawn that the constitutive model of damage and softening is reasonable through the comparison between the test data and the model data.
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Keywords:
- argillaceous siltstone /
- triaxial test /
- Weibull distribution /
- damage
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