郑济铁路郑璞段无砟道床裂纹分析及预防措施

Crack Analysis and Preventive Measures of Ballastless Track Bed in Zheng-Pu Section of Zheng-Ji Railway

双块式无砟道床在施工过程中不可避免的在轨枕周围出现“八”字裂纹,裂纹产生的因素整体归结于新浇筑混凝土塑性收缩裂纹、新旧混凝土收缩值不一致产生的张拉裂纹等。研究立足于郑济铁路郑璞段工程,通过水化热分析、强度分析、收缩值分析、pH值分析以及抗折强度分析等手段,旨在通过优选水泥、混凝土配合比以及新旧混凝土界面处理方式减少裂纹的发生。得出相关结论如下:(1)海螺水泥以低水化热、高强度、低收缩值是三种水泥中的最佳选择;(2)综合分析五种配合比抗压强度、pH值以及收缩值发展规律,优选出最佳配合比;(3)四种界面区的处理中,涂刷高性能无机界面剂以其抗折强度高、收缩值低等特点为最佳选择。应用实践表明,裂纹控制措施效果良好。

During the construction of double block ballastless track bed, it is inevitable to have splayed cracks around the sleepers, the factors causing the cracks are attributed to the plastic shrinkage cracks of newly poured concrete and the tension cracks caused by the inconsistent shrinkage values of old and new concrete. Based on the project of Zheng-Pu section of Zheng-Ji railway, through the analysis of the hydration heat, strength, shrinkage value, pH value and flexural strength, the research aims to reduce the occurrence of cracks by optimizing cement, the mix proportion of concrete and the treatment of the interface between old and new concrete. The relevant conclusions areas follows:(1)CONCH cement with low hydration heat, high strength, low shrinkage value is the best choice among the three cements;(2)Through the comparison of the development laws of compressive strength, pH value and shrinkage value of five concrete with different mix proportions, the optimum mix proportion is determined;(3)Among the four kinds of interface transition zone treatment, brushing high-performance inorganic interface agent is the best choice because of its advantages of high flexural strength and low shrinkage value.The application practice shows that the crack control measures are effective.