岩石弹脆性分维损伤本构模型

本文定义岩石构元中破裂面的分维值为各向同性损伤变量,而各个方向上裂纹面的累加量定义为各向异性损伤变量,并根据裂纹发育特征提出了损伤变量演化方程,从而建立起岩石脆性变形破坏过程的分维损伤本构模型。最后,利用该模型对大理岩单轴压缩应力应变曲线进行了模拟,结果说明本文提出的模型是较为合理的。

THE FRACTAL DAMAGE CONSTITUTIVE MODEL OF ROCK MATERIALS

The brittle failure of compressed rock materials is a process during which large quantities of microdamages(microcracks or microtcavities) nucleate, develop and coalesce. lt is a very complicated nonlinear evolutionary process. ln the present work, the fractd damage consdtitutive relation for the deformation and brittle failure of rock materials is proposed based on the test results and statistical calculations. The damage variables are defined according to the characteristics of rock media which contain plenty of microcracks and mdcrocavides. The definition has a clear physical meaning, and reflects the combined effects of large amount of distributing cracks of rock materals . The mathematical expression of constitutive relation was determined within the thermodynamjcal framework. The evolutionary equations of damage variables reflecting both isotrpic and anisotropic properties are proposed. Together, they . form the elasto-brittle damage consdtitutive relations for rock materials . Finally, the constitutive model is verified by the expermental result of uniaxial compression test of marble specimens. The result shows that this model is suitable in simulating the mechanical behaviours of rock materials . The nature of fractal distributed phonomena means that they have no characteristic scale. There are a lot of papers reporting the fractal distribution of rock fracture on the earth surfaces. Therefore, besides to solve rock engineering problems, the model proposed by this work can probably also be used to compute large scale mechanical problems or applied to the invesdgation of geodynamics or earthquakes.