非均质岩石时效力学性能多尺度研究

Claystone is one of the important candidate hosting rocks for high-level waste geological repositories. Its microstructure consists of various mineral components and complex pore structures. The heterogeneity feature is very obvious, which directly affects its macroscopic time-dependent mechanical behaviors. In this project, the claystone in the pre-selected area of Tamulin was taken as the research object, and the indoor microscopic and macroscopic time-dependent experiments were carried out. The influence of the microstructure characteristics of claystone on its macroscopic time-dependent mechanical behavior is revealed from microscopic scale. .Based on the experimental results and using the micromechanical theory with homogenization method, a strength failure criterion will be derived which takes into account simultaneously the effects of porosity, volume fraction of mineral composition and matrix properties. The microscopic evolution equations of porosity, inclusion’s volume fraction, softening or hardening of matrix, the interfacial debonding due to inconsistent deformation in the matrix and inclusions are established in order to show the changes of microstructure with time and loading. Then, a unified elastoplastic-viscoplastic multi-scale time-dependent model will be proposed to reveal the mechanism of the physical and mechanical properties of microstructure on the instantaneous and creep deformation of heterogeneous materials. The proposed micro-Macro model will be applied to solve engineering problems.

粘土岩是高放废物地质处置库重要的候选围岩之一, 其微观结构组成含有多种矿物成分和复杂的孔隙结构，表现出明显的非均质性特征。这种非均质结构直接影响到其宏观时效力学特性。本项目以塔木素预选区粘土岩为研究对象，开展室内细观和宏观时效力学试验研究。从细观尺度来揭示粘土岩细观结构特征对其宏观时效力学性能的影响。以试验结果为基础，运用细观力学理论和均匀化方法，提出同时考虑非均质岩石孔隙率，矿物成分含量，基质性质等细观特征的强度破坏准则。建立孔隙率和矿物夹杂含量变化、基质软硬化、基质和夹杂间由于变形不协调不一致而导致的界面脱离（debonding）等细观特征演化方程来表征微观结构时效变形演化过程。继而建立统一的弹塑性-粘塑性多尺度时效力学模型来揭示细观结构物理力学特性对材料的瞬时和蠕变变形作用机制，并实现工程应用 。

细观结构对非均质岩石材料宏观力学性能的影响近年来受到了广泛关注。基于材料的细观结构来建立多尺度本构模型对进一步认识，理解深部岩石工程破坏特征和机理有重要意义。本项目根据非均质岩石的细观结构和细观力学理论，具体研究了孔隙率、矿物夹杂含量和固体基质性质对材料宏观力学强度的影响，对于不同的细观结构，建立了各自对应的解析宏观屈服准则，和对应的考虑细观结构及其演化(如非均质相含量的变化，基质和夹杂间的界面脱离等)的本构模型。进一步建立了统一的弹塑性-粘塑性多尺度时效力学模型来揭示细观结构物理力学特性对材料的瞬时和蠕变变形的作用机制，并实现了工程应用 。