为研究道床裂纹对无砟轨道受力的影响,根据道床裂纹的特点,基于线弹性断裂力学理论,构造20节点六面体奇异等参单元反映裂纹尖端奇异,建立含裂纹的无砟轨道空间有限元模型,分析无砟轨道的受力特性.结果表明:道床裂纹对钢轨和道床板垂向位移影响较小,对道床板中上部混凝土及钢筋受力的影响不明显,道床下层钢筋应力在裂纹处发生突变,静态和动态裂纹宽度基本相同;对于道床底面60 mm等深裂纹,在列车荷载作用下,裂纹处钢筋应力增大为未开裂时的2倍左右,裂纹张开0.017 mm.
The support layer is an important component of twin-block ballastless track.The modulus of the support layer is an important design parameter and must be carefully solved.We studied the bending stress and deformation of track slab and support layer due to train load using the beam-plate finite element model on elastic foundation.The results show that support layer type has great impact on both support layer deformation and the stress on subgrade,but has little impact on the bending stress of either track slab or support layer.The continuous support layer type,and articulated support layer type with shear transfer device at their ends,are recommended.In order to keep the stress in the support layer less than that in track slab,the modulus of the continuous,unit,and articulated types of support layer(in unit twin-block ballastless track),and the support layer in continuous twin-block ballastless track,should not be larger than 15,22,20.5 and 5 GPa,respectively.In addition,the modulus of the unit-type support layer should not be more than 20 GPa,to ensure the step in support layer remains less than 1 mm.
