基于CT图像的混凝土细观结构的有限元重建

Reconstructing finite element model of concrete meso-level structure with CT scanning image

基于CT扫描得到的图像,结合图像数字处理技术,对混凝土的真实细观结构进行了重建,并将其导入有限元软件之中,建立了更能准确表征混凝土细观非均质性的二维数值试件,尤其是考虑了孔隙对混凝土拉应力分布的影响,从而弥补了传统数值方法中采用虚拟随机混凝土骨料模型的不足。通过几种不同情况的劈裂试验的对比,可以发现,是否考虑非均质性和孔隙将会对计算结果产生很大的影响,考虑了混凝土的非均质性和孔隙后,拉应力分布并不是均质条件下的中心对称均匀分布,而是有大量应力集中现象,主要出现在骨料、砂浆基质和孔隙的交界处,拉应力沿加载方向呈波动状变化,最大拉应力出现在孔隙和砂浆基质的交界处,而不是出现在沿加载方向直径的中心附近。

A 2-D finite element model of concrete meso-level structure is reconstructed by digital image processing with CT scanning image.The heterogeneity described is more approaching to the actual concrete meso-level structure.Especially considered the influence of voids on the tension stress distribution,thereby overcomes the shortage of traditional Random Aggregate Model（RAM ）.Three different models of concrete indirect tensile test contrast indicated that the heterogeneity and the voids tremendously influenced the computed result.The tension stress concentration, which not occurred in the homogeneous model, mainly appeared on the surface between voids and aggregates.The maximal tension stress along the loading axis of the model was also appeared on the surface between voids and aggregates.