CRTS Ⅱ型轨道板裂缝宽度的变化规律

Change Rule of Crack Widths of CRTS Ⅱ Track Slab

为研究轨道结构的纵连成型过程对轨道板裂缝的影响,建立了1/4单元轨道板的分离式模型,对轨道板裂缝问题进行了分析.通过研究轨道结构的纵连成型过程,指出Ⅱ型板具有独特的纵连特征和结构特征,以该特征为研究基础,分析了轨道板在整体降温30℃和40℃作用下板端和板中裂缝宽度的影响因素和变化规律.研究结果表明:随着轨道板与砂浆层层间粘结状态的弱化,板端裂缝宽度ω_k略微增大,板中裂缝宽度ωz略微减小,板中不开裂时,ω_k最大增加0.032 1 mm,板中开裂时,ω_k最大增加0.026 9 mm,ωz最大减小0.024 4 mm;对ω_k影响最大的因素是宽接缝硬化时张拉钢筋端部的初始应力和窄接缝承力大小,以及板中是否开裂;对ωz影响最大的因素是宽接缝硬化时张拉钢筋端部的初始应力,且其减小的越多,ωz越小;轨道板的纵连特征使得ω_k和分布不均匀,纵连钢筋偏弱又使得ω_k数值较大,整体降温30℃和40℃时,ω_k的变化范围分别为0.182～1.906 mm和0.389～2.546 mm,且普遍大于ωz,这与目前Ⅱ型板式轨道的裂缝开裂特征相一致.

To study the influence of longitudinal connection forming process of track structure on track slab cracks,a 1/4 unit track slab separate model was established,and the crack problems were analysed.By studying the track structure longitudinal connection forming process,Ⅱslab was found to have unique longitudinal connection and structure characteristics.Based on these,the influencing factors and the change rule of crack widths both in the middle and at the end of track slab were analysed,respectively,when its temperature decreased 30℃and 40℃.The results show that with the bonding state weakening between the track slab and mortar layer,the crack width at the end of track slabωk increases slightly,while the crack width in the middle of track slabωz decreases slightly;ωk can be increased by 0.032 1 mm at most if track slab has no cracks.Moreover,ωk can be increased by 0.026 9 mm at most andωz can be decreased by 0.026 9 mm at most if the track slab has a crack in the middle.The most influential factors onωk are the initial stress at the end of tensioned rebars,and the initial compressive stresses of narrow joints when wide joints harden;there is also the question of whether track slab has a crack in the middle or not.The initial stress at the end of tensioned rebars,when wide joints harden,is the most influential factor onωz,and the more it decreases,the smallerωz is.Bothωk andωz are distributed unevenly as a result of the longitudinal connection characteristic of track slab,and the numerical value ofωk is large because of the weak connection between track slabs.When track slab temperature decreases 30℃and 40℃,respectively,numeric rangesωk of are 0.182–1.906 mm and 0.389–2.546 mm respectively,andωk is larger thanωz usually,which are consistent with the crack characteristics ofⅡslab track at present.