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为实现岩石试样蠕变全过程的准确模拟,并从细观角度探究蠕变过程中微裂隙的发生和发展规律,在二维颗粒流程序(PFC2D)中开发出具有黏弹塑性特征的西原体流变接触本构模型,进一步提出包含两种非定常元件的非定常西原体模型,推导了模型本构关系和蠕变方程.在PFC2D中调用自定义西原体流变模型,通过参数调试,获得与真实试样具有相同强度特性的数值试样.以室内单轴压缩蠕变试验数据为基础,在Matlab中对模型非定常参数进行拟合反演分析.在此基础上,进行单轴压缩蠕变试验的模拟,计算过程中分别采用定常和非定常两种模型,并对微裂隙进行监测.对比分析结果表明:定常模型仅适用于衰减和稳定蠕变阶段;非定常模型也可用于描述加速蠕变阶段,从而准确模拟蠕变全过程;加速蠕变阶段主要是由微裂隙的加速发展而产生,加速蠕变将导致试样剪切破坏.
In order to accurately simulate the entire creep process of rock samples and investigate the occurrence and development of micro-cracks in the creep process from a microscopic point of view, we developed the Nishihara (Visco-Elasto-Plastic) feature in a two-dimensional particle flow program (PFC2D) The body fluid rheological contact constitutive model is further proposed, which includes two kinds of unsteady elements, and the constitutive relation and creep equation of the model are deduced.The self-defined rheological model is called in PFC2D, A numerical sample with the same strength characteristics as the real sample was obtained.The fitting and inversion analysis of the unsteady model parameters was carried out in Matlab based on the uniaxial compressive creep test data in the laboratory.On this basis, Creep tests are simulated and the steady and unsteady models are used respectively, and the micro-cracks are monitored.The results of the comparative analysis show that the steady model is only suitable for the decay and steady creep stages, and the unsteady model can also be used to describe Accelerate the creep stage, and thus accurately simulate the entire process of creep; accelerated creep stage is mainly caused by the accelerated development of micro-cracks, accelerated creep will lead to specimen shear failure.