CRTSⅢ型高铁轨道现浇底座板裂缝分析及控制

Analysis and control of cracks in the cast-in-situ base plate of CRTSⅢ high speed rail

根据项目所用的原材料、配合比、结构尺寸及约束特征进行了抗裂验算,根据验算结果和裂缝分布特征,推断CRTSⅢ型高铁现浇轨道底座板开裂是由收缩引起的,针对该裂缝,引入兼有抗裂、减缩和增强密实作用的高性能纤维复合材料SY-COM,并进行了和易性、抗压、劈裂抗拉和刀口诱导开裂试验。结果表明:与基准组相比,该材料可降低泌水率,对工作性无不利影响,28 d抗压强度提高0.03%,28 d劈裂抗拉强度提高1.14%,刀口诱导抗裂试验评定结果为Ⅰ级。工程应用和自生收缩试验表明:与原方案相比,掺入SY-COM使混凝土28 d自生收缩降低了56.2%,抗裂安全系数提高了63.1%,使前述推断得到了验证,该方案可行。

According to the raw materials,mix proportions,structural dimensions and constraint characteristics used in the project,the crack resistance calculation was carried out.According to the calculation results and crack distribution characteristics,it was concluded that the crack of CRTSⅢcast-in-place rail base plate was caused by shrinkage.For this crack,a high-performance fiber composite material SY-COM with the functions of crack resistance,shrinkage reduction and densification enhancement was introduced,and the workability,compression,splitting tension and knife-edge induced cracking tests were carried out,The results show that compared with the reference group,this material can reduce bleeding rate without adverse effects on workability.The compressive strength at 28 days is increased by 0.03%,the splitting tensile strength at 28 days is increased by 1.14%,and the evaluation result of blade induced cracking resistance test is levelⅠ.The engineering application and autogenous shrinkage test results show that compared with the original plan,the addition of SY-COM reduces the spontaneous shrinkage of concrete by 56.2%after 28 days,improves the safety factor of crack resistance by 63.1%.This confirms the above inference and proves the feasibility of this plan.