铁道建筑

重组竹材具有负碳属性，经碳化后替代传统材料轨枕具有很大潜力，但针对重组竹轨枕的研究缺少足尺试验。本文设计了采用两种厚度排布方式胶合的碳化重组竹轨枕，使用数字图像相关（Digital Image Correlation,DIC）技术研究竹轨枕在三点抗弯和四点抗弯试验下的轨枕挠度、裂纹特性以及破坏形式。结果表明：碳化重组竹轨枕的极限承载力最高可达292.445 kN （三点抗弯）和414.525 kN（四点抗弯），远高于混凝土轨枕和木枕，抗弯刚度和延性介于混凝土轨枕和木枕之间。厚度排布方式对碳化重组竹轨枕的极限承载力和破坏形式影响较小，但会直接影响轨枕的层间裂纹和断裂位置。碳化重组竹轨枕受弯过程均处于弹性状态，达到极限承载力后发生断裂，其破坏形式为沿着或靠近中性层的胶合面处层间剪切破坏。在三点抗弯试验中，竹轨枕沿着主裂纹方向断裂；在四点抗弯试验中，沿着或靠近枕中截面中性层位置的裂纹断裂。碳化重组竹轨枕的极限承载力、抗弯刚度和延性完全满足铁路轨枕设计要求，可应用于重载铁路和客货共线铁路正线有砟轨道。

Reconstituted bamboo has negative carbon properties and great potential to replace traditional material sleepers after carbonization. However, research on reconstituted bamboo sleepers lacks full-scale testing. This article designed carbonized reconstituted bamboo sleepers bonded with two different thickness arrangements, and used Digital Image Correlation(DIC) technology to study the deflection, crack characteristics and failure modes of bamboo sleepers under three-point and four-point bending tests. The results show that the ultimate bearing capacity of carbonized reconstituted bamboo sleepers can reach up to 292.445 kN(three-point bending test) and 414.525 kN(four-point bending test), which is much higher than that of concrete sleepers and wooden sleepers. The bending stiffness and ductility are between those of concrete sleepers and wooden sleepers. The thickness arrangements method has little effect on the ultimate bearing capacity and failure mode of carbonized reconstituted bamboo sleepers, but it directly affects the interlayer cracks and fracture positions of the sleepers. Carbonized reconstituted bamboo sleepers are in an elastic state during the bending process, and fracture occurs after reaching the ultimate bearing capacity. The failure mode is interlayer shear failure along or near the bonding surface of the neutral layer. In the three-point bending test, the bamboo sleeper fractured along the direction of the main crack. In the four-point bending test, cracks fracture is along or near the neutral layer position in the cross-section of the sleeper. The ultimate bearing capacity, flexural stiffness, and ductility of carbonized reconstituted bamboo sleepers fully meet the design requirements of railway sleepers and can be applied to ballasted tracks on heavy haul railway and mixed passenger and freight railway.