夏季高温下支承层斜裂缝诱发纵连板上拱规律研究

Study on Arching Pattern of Continuous Ballastless Slab Track Induced by Oblique Crack in Concrete Base under High Temperature in Summer

在夏季高温作用下,支承层斜裂贯通缝可能导致结构上拱变形,衍生次生病害。基于内聚力和塑性损伤理论建立CRTSⅡ型板式无砟轨道结构有限元模型并与现场实测结果对比验证模型的有效性,分析夏季高温作用下支承层斜裂缝导致的结构上拱变形、离缝、受力和伤损规律。结果表明,温度荷载作用下,斜裂缝一旦贯通,轨道结构变形急剧增大。随温度升高,支承层相互错动,CA砂浆层与支承层先离缝,随后轨道板与CA砂浆层离缝,轨道结构上拱变形。结构性能随温度演化过程可分为0~20℃的缓慢发展阶段、20~30℃的加速发展阶段和大于30℃的飞速破坏阶段。贯通斜裂缝位于板中,角度30°时,轨道结构变形达到最大值26 mm。建议温度大于30℃时,检修重点关注角度不大于45°的板中斜裂贯通缝。

Oblique crack damage in the concrete base of ballastless slab track may result in arch deformation and secondary damages under the influence of high temperatures in summer.In order to analyze the arch deformation,delamination,stress,and damage caused by oblique cracks in the concrete base under high temperatures in summer,a finite element model of the CRTSⅡslab ballastless track structure was established based on the cohesive zone model and the concrete plastic damage model.The effectiveness of the model was verified by comparing it with on-site measurement results.The findings demonstrate that in the case of oblique crack penetration,the track structure begins to deform rapidly under the temperature force.The concrete base dips offset as the temperature rises.The track construction deforms into an arch as a result of the gap that first forms between the CA mortar layer and the concrete base,then between the track slab and the CA mortar layer.The gradual development stage from 0 to 20℃,the accelerated development stage from 20 to 30℃,and the quick destruction stage over 30℃are the three stages of the evolution of structural properties with temperature.The maximum deformation of the track construction is 26 mm when the oblique fracture is positioned in the center of the precast track slab at an angle of 30°.It is recommended to focus on the oblique cracks that are located in the center of the precast track slab with an angle not exceeding 45°,when the temperature exceeds 30℃.