CRTSⅡ型板式轨道假缝开裂对轨道受力的影响分析

The Impact of Dummy Joint Cracking in CRTSⅡSlab Track

为分析CRTSⅡ型板式无砟轨道假缝开裂对轨道受力性能的影响,以桥上Ⅱ型板式无砟轨道为例建立模型,应用有限元法,计算分析不同数量和不同深度的假缝裂缝在不同荷载作用下对Ⅱ型板式轨道受力性能的影响。结果表明,对比列车荷载和温度梯度的影响,正温度梯度作用下,假缝开裂对轨道结构的受力影响最大,裂缝深度小于200 mm时,裂缝处混凝土会发生局部受压破坏;裂缝深度达到200 mm时,开裂会导致底座板和砂浆层的连带破坏;随着开裂数量的增加,砂浆层和底座板的应力峰值减小。不同荷载作用下,假缝开裂都会导致裂缝处纵连钢筋应力的突变,但不会导致纵连钢筋的屈服破坏。

In order to analyze the impact of the dummy joint cracking on CRTSⅡ slab track, the model of CRTS II slab track on bridge is built. Through finite element method, the influences of different quantity and depth of the dummy joint cracking on CRTS II slab track under different loads are calculated and analyzed. The results show that the track structure is most adversely affected under positive temperature gradient in comparison so far as train load and temperature gradient are concerned. When the crack depth is less than 200mm, the local concrete at the crack fails under pressure. When the crack depth reaches 200mm, the cracking will lead to the destruction of the concrete base and the mortar layer. With the increase of the cracking, the maximum stress of the concrete base and mortar layer decreases. The cracking of the dummy joint will result in prompt change of reinforcing bar stress, but not in the yield failure of the longitudinal reinforcing bar.