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对滇藏铁路三江段的花岗岩进行了单轴和常规三轴压缩试验,研究了岩石在不同围压条件下的变形特性及其损伤演化规律。试验结果表明:该岩石压缩变形过程中,内部裂隙的演化经历了无起裂、起裂并稳定扩展、加速扩展、扩展变缓以及扩展停止5个阶段,且围压对岩石变形特性有显著影响。在此基础上,提出了基于有损微元生成的损伤演化模型,建立了三轴压缩条件下岩石应变软化损伤本构模型。该模型能够统一描述岩石峰前及峰后全部变形特性及其损伤演化规律,且损伤方程形式简单、参数物理意义明确。理论结果和试验数据具有很好的一致性,且参数分析结果也表明了该模型的合理性。
Uniaxial and conventional triaxial compression tests were conducted on the granites in the Sanjiang section of the Yunnan-Tibet Railway, and the deformation characteristics and damage evolution of the rocks under different confining pressures were studied. The results show that during the process of compressive deformation of the rock, the evolution of the internal fissures undergoes five stages of no fissure, rupture and stable expansion, accelerated expansion, slowing down and expansions, and the confining pressure has a significant effect on the deformation characteristics of the rock . Based on this, a damage evolution model based on lossy micro-elements is proposed and a strain-softening damage constitutive model for rock under triaxial compression is established. The model can describe all the deformation characteristics and damage evolution law before and after peak rock, and the damage equation is simple in form and the parameters have clear physical meaning. The theoretical results are in good agreement with the experimental data, and the results of parametric analysis also show the rationality of the model.