基于细观均匀化的膨润土有效热传导特性研究

An effective thermal conductivity model for bentonite based on meso homogenization techniques

基于均匀化方法和椭球夹杂问题基本解给出了非饱和岩土体的有效热传导特性模型。该模型可以考虑夹杂形态、体积分数和空间分布及夹杂间相互作用对有效热传导特性的影响,反映了由于非均匀夹杂引起有效热传导张量的各向异性特性。讨论了夹杂宽高比以及夹杂与基质热传导系数比对有效热传导张量各向异性系数的影响。将岩土体看作固体基质和孔隙夹杂构成的非均匀材料,探讨了岩土体有效热传导系数随孔隙形态、孔隙率和饱和度的变化规律。最后,应用上述模型对高庙子膨润土(GMZ01)有效热传导系数进行预测并与其他模型预测结果进行对比分析。研究表明,本文模型对GMZ01膨润土有效热传导系数具有较好的预测能力,但更准确的预测需根据膨润土的孔隙结构采用多层次均匀化方法。研究成果对于高放核废料深地质处置库缓冲材料的热-水-力耦合特性具有一定参考价值。

An effective thermal conductivity model is presented based on the basic solution of ellipsoidal matrix-inclusion problem using homogenization techniques.This model integrates well the effects of the shape,volume fraction,space distribution of inclusion and the interaction between inclusion and matrix on the effective thermal conductivity.The anisotropy of conductivity,which is mainly induced by the aspect ratio of inclusion and the ratio between conductivity of inclusion and matrix,is also included in the model.On this basis,by characterizing the geomaterials as heterogeneous media composed of solid matrix and embedded ellipsoidal voids,the influences of void shape,porosity and saturation degree on the effective thermal conductivity are discussed.Finally,the proposed model is used to predict the effective thermal conductivity of Gaomiaozi bentonite（GMZ01）;and the predicted results are compared with the experimental data and the predictions by other models.The results show that the proposed model has a better predictive capability for the effective thermal conductivity of the GMZ01 bentonite.Given the complex pore structure of the bentonite,multiscale homogenization techniques should be used to yield more accurate predictions.The research results may provide a helpful reference for better understanding the coupled thermo-hydro-mechanical behaviors of buffer materials for the high-level radioactive waste disposal.