Gaps under CRTS Ⅱ slab appeared during the hot season in the early stage of the operation of the CRTS Ⅱ slabs,which will seriously affect the normal operation of the high-speed trains and the durability of the track structure.In this paper,a refined vehicle-track spatial coupling dynamic model was established considering the gap between the slab and CA mortar to study the dynamic responses of the vehicle-track structure during the operation under the gap condition,and to analyze the effect of different gap sizes,scopes and vehicle speeds.The results showed that the increase of the gap magnitude would aggravate vehicle-track dynamic response.The aggravation was more significant with the magnitude of the gap being at more than 6 ～ 8 mm.The wheel-rail vertical force,and the longitudinal stress of the rail,CA mortar,as well as the track slab were more significant when the gap appeared in two track slabs.Thus,more attention should be paid to the gap appearing in two track slabs during track maintenance.Temporary velocity limiting in gap area was an effective method to ensure the safety of train operation and to reduce the stress of track structures.The conclusion obtained in this paper provides a reference and recommendation for the velocity limitation in gap area.%CRTSⅡ型板式无砟轨道在运营初期高温季节中出现区域性板下离缝现象,影响高速列车正常运营和轨道结构耐久性.本文建立考虑轨道板和CA砂浆阈离缝的精细化车辆-轨道空间耦合动力学分析模型,分析离缝状态下车辆、轨道的动力学响应,研究不同离缝量、离缝范围及车辆行车速度的影响.结果表明:离缝量增加导致车辆、轨道动态响应加剧,离缝量在6～8 mm以上时加剧效应明显;离缝范围在2块板下导致的轮轨垂向力及钢轨、砂浆层纵向应力更明显,轨道板纵向应力也较大,因此在养护维修时应重点关注离缝范围在2块板下的情况;离缝区域临时限速是保证列车运营安全、降低轨道结构应力的有效手段,本文提出的限速建议值可为离缝区域限速运营提供参考.
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