冻融-荷载作用下基于残余强度特征的岩石损伤模型

Rock damage constitutive model based on residual intensity characteristics under freeze-thaw and load

  • 摘要: 岩石变形破坏特性是寒区岩土工程建设所直接面临的基础力学问题。为模拟冻融与荷载作用下岩石变形破坏的全过程,将冻融-荷载作用下的岩石微元在轴向抽象为未损伤、冻融损伤、受荷损伤、冻融与荷载共同损伤4部分,这4部分材料共同承受轴向应力,其中冻融损伤、受荷损伤、冻融与荷载共同损伤3部分可承受残余应力。采用Weibull分布描述岩石材料的非均匀性,基于D-P破坏准则,定量表述了冻融与荷载的耦合效应对总损伤的影响规律,建立了考虑残余强度特征的冻融受荷岩石损伤本构模型;基于岩石变形破坏特征,推导出模型参数的理论表达式;开展红砂岩冻融循环及三轴压缩试验,研究岩石的变形破坏过程及冻融循环和围压对其力学特性的影响,验证所建模型的合理性;分析冻融-荷载作用下岩石的损伤力学特性。研究表明:本文所建模型反映了冻融受荷岩石变形破坏的全过程,并能表征冻融循环和围压对岩石变形特性的影响;岩石的总损伤演化途径反映了细观力学响应与宏观变形破坏特征相一致,刻画出冻融与荷载2种作用因素对岩石总损伤扩展的非线性影响特性,探寻了细观损伤演化所诱发的宏观力学效应,为揭示岩石的冻融破坏机制提供理论依据。

     

    Abstract: The deformation and failure characteristics of rock are the fundamental mechanics problems directly faced in a geotechnical engineering construction project in cold region. To simulate the whole process of rock deformation and failure under freeze-thaw and load,the rock micro-elements in the axial direction are abstracted into four parts:the un- damaged part,the freeze-thaw damaged part,the loading damaged part and the coupling damaged part of freeze-thaw and load,and the axial stress is supported by the four parts together,with the three damaged parts can share the resid- ual stress. Using the Weibull distribution to describe the heterogeneity of rock materials,the coupling effect of the freeze-thaw and load on the total damage is expressed quantitatively based on the D-P failure criterion,and the damage constitutive model based on the characteristics of the residual strength is established for freeze-thaw and loaded rock.In terms of rock deformation and failure characteristics,the theoretical expression of the model parameters is derived. To verify the rationality of the model,the freeze-thaw cycle and triaxial compression tests of the red sandstone is con- ducted,the law of rock deformation and failure is analyzed,the effects of freeze-thaw cycles and confining pressure on their mechanical properties are revealed. It is shown that the damage model reflects the whole process of deformation and failure of freeze-thaw and loaded rock,at the same time,the effects of freeze-thaw cycles and confining pressure on the deformation properties of rock can be characterized. The evolution path of total damage reflects the consistency of the micro-mechanical response and macroscopic characteristics of the deformation and failure of rock,and the nonlin- ear influence characteristics of freeze-thaw and load on total damage expansion is portrayed,the macroscopic mechani- cal effects induced by mesoscopic damage evolution are explored which can provide a theoretical basis for revealing the mechanism of rock freeze-thaw damage.

     

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