Study on the non-linear deformation and failure characteristics of EPS concrete based on CT-scanned structure modelling and cloud computing
Study on the non-linear deformation and failure characteristics of EPS concrete based on CT-scanned structure modelling and cloud computing
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基于CT扫描结构建模和云计算的EPS混凝土非线性变形破坏特性研究
DOI：
10.1016/j.engfracmech.2021.108214
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发表时间：
2022
影响因子：
5.4
通讯作者：
Feng X
中科院分区：
文献类型：
--
作者：
Feng X
为了解发泡聚苯乙烯（EPS）混凝土的复杂变形特征和破坏机理，揭示发泡聚苯乙烯微珠和聚丙烯纤维的复合效应，对EPS混凝土浇注试件进行了一系列试验研究。同时，建立了三维真实破坏过程分析云计算系统RFPA 3D，对真实的混凝土结构进行了精细破坏过程建模。通过CT扫描获得EPS混凝土试件的微观形貌，并利用数字图像处理技术对其进行进一步处理。采用大津算法自动识别各分区图像的分割阈值，设计了CT图像处理程序，实现了数字图像的自动分割与融合。然后，利用处理后的数字图像建立了反映EPS混凝土试件微观结构的数值模型，并利用基于云计算的RFPA3D进行了一系列三维数值模拟。结果表明，低EPS体积分数混凝土的破坏形态为非光滑凸台阶状，具有典型的脆性断裂特征。相比之下，韧性断裂发生在具有高EPS体积断裂的混凝土中。同时，加入一定长度的聚丙烯纤维可以有效地防止水泥基体中新裂缝的形成和扩展。此外，混凝土的峰值强度随着均匀性的增加而增加，而剩余强度通常随着均匀性的增加而降低。此外，一个更不均匀的材料提出了更多的宏观断裂前的声发射前兆。这些成果极大地提高了我们对EPS混凝土在土木工程中的设计、施工和维护的认识。
To understand the complex deformation features and failure mechanisms of expanded polystyrene (EPS) concrete and reveal the composite effect of expanded polystyrene beads and polypropylene fibers, a series of experiments were conducted on the poured EPS concrete specimens. Meanwhile, a cloud computing system for 3D realistic failure process analysis (RFPA3D) was established to model the fine failure process of a real concrete structure. The micromorphology of the EPS concrete specimens was obtained via CT scanning and further processed using digital image processing technology. The Otsu algorithm was applied to automatically recognize the segmentation thresholds of each partition image and a procedure for CT image processing was designed to automatically realize digital image segmentation and merging. Then, the numerical models reflecting the microstructures of the EPS concrete specimens were built using the processed digital images and a series of 3D numerical simulations were performed using cloud-computing-based RFPA3D. The results show that for concrete with low EPS volume fracture, the non-smooth convex-step-shaped failure morphology, which is a typical brittle fracture characteristic, appears. In contrast, ductile fracture occurs for concrete with a high EPS volume fracture. Simultaneously, the addition of polypropylene fibers of a certain length can effectively prevent the formation and expansion of new cracks in the cement matrix. In addition, the peak strength of concrete increases with an increase in homogeneity while the residual strength generally decreases with an increase in homogeneity. Moreover, a more heterogeneous material presented more acoustic emission precursors before macro fracture. All these achievements greatly improve our knowledge of the design, construction, and maintenance of EPS concrete in civil engineering.