动荷载与水耦合作用下无砟轨道混凝土层间裂纹扩展研究

随着高速铁路的大范围应用,无砟轨道在列车荷载与水耦合作用下的水致损伤问题备受关注。为研究列车荷载与水耦合作用下无砟轨道层间裂纹扩展现象,运用有限元软件进行无砟轨道层间裂纹扩展分析,开展动荷载与水耦合作用下的混凝土层间裂纹扩展试验。研究结果表明:裂纹尖端疲劳寿命与列车速度呈二次方关系,随列车轴重增加,裂纹尖端疲劳寿命显著降低;裂纹尖端剪应力随裂纹深度增大呈高次方增长;裂纹扩展初期尖端多呈一定弧度,裂纹局部会伴有压溃现象;混凝土层间裂纹沿界面扩展时为折线形,并可能会产生裂纹分叉,最终导致裂纹面掉块现象发生。

Experimental Research on Crack Propagation between ballastless track Layers of Concrete Subject to Dynamic Load and Water Coupling

With the large-scale application of high-speed railway, the water-induced damages of ballastless track under the coupling of train load and water have attracted much attention. In order to study the crack propagation mechanisms of the ballastless track under the coupling of train load and water,the finite element software is used to analyze the crack propagation in the ballastless track,and crack propagation tests are carried out under the coupling action of dynamic load and water. The results show that the fatigue life of the crack tip has a quadratic relationship with the train speed,and with the increase of the axle load,the fatigue life is significantly reduced; shear stress at the crack tip tends to increase with crack depth increase by high power. The results also show that the initial crack tends to grow in curve and part of the crack is crushed; concrete cracks along the interface between the layers expand in polygonal-shape,and may produce crack bifurcate,leading to crack face off-falling.