假缝设置间距对道床板裂缝性能的影响

Influence of false seam spacing on crack performance of bed slab

为实现假缝设置对道床板裂缝发育的有序引导及其裂缝性能的控制,针对假缝设置间距对相邻假缝间轨道力学状态和假缝处裂缝性能的影响展开研究。基于理论推导建立假缝设置间距与假缝处裂缝宽度和钢筋应力的数学关系,结合现场试验验证,提出假缝设置间距计算方法,并分析其适用环境及应用建议。研究结果表明:假缝处裂缝宽度和钢筋应力均随着假缝设置间距减小而降低,在温降不大于25°C的一般温度环境地区,1.0~6.0m范围内的假缝设置间距降低50%,对应的裂缝宽度和钢筋应力将分别降低约50%和28%;改变假缝设置间距可以灵活控制裂缝宽度,但对于降低钢筋应力的能力却存在上限;线路所处地区的温降越大,满足其裂缝宽度控制要求的假缝设置间距上限越小,对应的钢筋应力下限越高;此外,道床板设置假缝时,其上层钢筋的断开对裂缝性能影响较小。

In order to realize the order guidance of the cracks and the control of the crack performance of the bed slab by the false seams setting, the influence of the false seam spacing on the crack performance at the false seam and the mechanical state of the track structure between false seams were studied. The mathematical relationships between the false seam spacing and the crack width, the steel stress at the false seam setting were established by theoretical derivation. Combined the field test verification and actual engineering, the applicable environment and application suggestions for the calculation method of the false seam spacing parameter were proposed. The results show that both the crack width and the steel stress decrease as the false seam spacing decreases. If the distance between adjacent false seams in the range of 1.0 m to 6.0 m is reduced by 50%, in the general temperature environment where the temperature drop is not more than 25 °C, the corresponding crack width and steel stress reduce by about 50% and 28%, respectively. The change of the false seam spacing can flexibly control the crack width, but it has an upper limit on the ability to reduce the steel stress amplitude. The larger the temperature drop in the area where the bed slab is located, the smaller the upper limit of the false seam spacing that meets the crack width control requirements, and the lower the lowest value of the corresponding steel stress. In addition, when the bed slab is set with a false seam, the disconnection of the upper reinforcement in bed slab has little effect on the crack performance.