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岩石的破坏是一个渐进的过程 ,其宏观破裂是局部化非均匀变形积累 (发展 )到一定阶段的结果。基于这一思想 ,对岩石 (大理岩 )从宏观力学全过程、应变梯度和分岔理论分析进行了研究。首先 ,从宏观力学方面对岩石 (大理岩 )单轴压缩和等围压三轴压缩全过程进行了系统研究。在单轴压缩试验中 ,岩石强度随应变率的增加而增加 ,峰后塑性区变形则随应变率的增加而减小 ,但应变率小于 10 -5/s时 ,影响不大 ;岩石试件平均应变与试件中部应变的差别随应变率的增加而变大。在峰前和峰后循环过程中 ,研究了塑性滞环、变形和切线模量特征 ,发现试件平均应变和中部应变有不同的发展过程。在全过程线基础上 ,进行损伤本构关系和塑性可膨胀本构关系的模型研究。在等围压三轴压缩全过程中 ,研究了等围压三轴压缩全过程特征 ,得到了峰前、峰后卸围压全过程。结合三轴压缩全过程 ,进行了剪切断裂能分析 ,结果表明 :峰前卸围压过程剪切断裂能要比峰后卸围压及三轴压缩低很多。最后综合分析了岩石试件的单轴和三轴宏观破坏特征 ,为分岔分析提供了依据。其次 ,从宏观和细观两个方面对岩石 (大理岩 )进行应变梯度研究。宏观力学方面结合等围压三轴压缩过程 (压剪 )研究了宏观破坏面局部应变梯度的形成和发展的过程。细观力学?
Rock destruction is a gradual process. Its macro-rupture is the result of a certain stage of accumulation (development) of localized non-uniform deformation. Based on this idea, the rock (marble) is studied from the macroscopic mechanics, strain gradient and bifurcation theory analysis. Firstly, the whole process of uniaxial compression and isostatic confining pressure triaxial compression of rock (marble) was systematically studied from macroscopic mechanics. In the uniaxial compression test, the rock strength increases with the increase of strain rate, and the deformation of plastic zone decreases with the increase of strain rate, but the strain rate is less than 10 -5 / s. The rock specimen The difference between the average strain and the strain in the middle of the specimen increases with the increase of strain rate. During the pre-peak and post-peak cycles, the characteristics of plastic hysteresis, deformation and tangent modulus were studied. It was found that the average strain and the middle strain of the specimens had different development processes. On the basis of the whole process, the model of damage constitutive relation and plastic expansible constitutive relation is studied. In the whole process of isostatic confining pressure triaxial compression, the whole process of isostatic confining pressure triaxial compression was studied, and the whole process of unloading confining pressure before and after the peak was obtained. Combined with the whole process of triaxial compression, the shear fracture energy analysis is carried out. The results show that the shear failure energy of the pre-peak unloading confining pressure process is much lower than that after the peak unloading confining pressure and triaxial compression. Finally, the uniaxial and triaxial macroscopic failure characteristics of rock specimens are analyzed synthetically, which provides the basis for bifurcation analysis. Secondly, from the macro and micro aspects of the rock (marble) strain gradient study. In macroscopic mechanics, the process of the formation and development of local strain gradient in macroscopic failure plane was studied by the isostatic compression triaxial compression process (compression shear). Meso-mechanics?