Micromechanical analysis of damage in saturated quasi brittle materials
Micromechanical analysis of damage in saturated quasi brittle materials
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DOI：
10.1016/j.ijsolstr.2011.12.006
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发表时间：
2012-03
影响因子：
3.6
通讯作者：
N. Xie;Q. Zhu;J. Shao;Lihua Xu
中科院分区：
文献类型：
--
作者：
N. Xie;Q. Zhu;J. Shao;Lihua Xu
本文提出了饱和多孔准脆性材料损伤及相关非弹性变形的细观力学分析方法。在排水和不排水条件下，材料被随机分布的微裂纹削弱，并被间隙流体饱和。重点研究了压应力作用下的闭合裂纹。材料损伤与裂纹表面的摩擦滑动有关，用局部标量变量描述。材料的有效性能的确定使用线性均匀化的方法，Eshelby的夹杂物解决方案的基础上扩展到硬币形裂纹。在不可逆热力学框架下描述了微裂纹引起的非弹性行为。作为一个原始的贡献，被封闭的摩擦微裂纹削弱的饱和材料的势能被确定和制定为一个弹性部分和一个塑性部分，后者完全由微裂纹的摩擦滑动引起的总和。通过微裂纹处的局部有效应力的概念，在摩擦准则中考虑了流体压力的影响。结果表明，毕奥有效应力控制着总应变的演化，而太沙基有效应力控制着塑性应变的演化。此外，裂纹唇之间的摩擦滑动产生体积阻尼和流体压力的降低。将该模型应用于典型脆性岩石的排水和不排水三轴试验，并与试验结果进行了比较。
In this paper, we propose a micromechanical analysis of damage and related inelastic deformation in saturated porous quasi brittle materials. The materials are weakened by randomly distributed microcracks and saturated by interstitial fluid with drained and undrained conditions. The emphasis is put on the closed cracks under compression-dominated stresses. The material damage is related to the frictional sliding on crack surface and described by a local scalar variable. The effective properties of the materials are determined using a linear homogenization approach, based on the extension of Eshelby’s inclusion solution to penny shaped cracks. The inelastic behavior induced by microcracks is described in the framework of the irreversible thermodynamics. As an original contribution, the potential energy of the saturated materials weakened by closed frictional microcracks is determined and formulated as a sum of an elastic part and a plastic part, the latter entirely induced by frictional sliding of microcracks. The influence of fluid pressure is accounted for in the friction criterion through the concept of local effective stress at microcracks. We show that the Biot’s effective stress controls the evolution of total strain while the local Terzaghi’s effective stress controls the evolution of plastic strain. Further, the frictional sliding between crack lips generates volumetric dilatancy and reduction in fluid pressure. Applications of the proposed model to typical brittle rocks are presented with comparisons between numerical results and experimental data in both drained and undrained triaxial tests.