北京新机场线高架地段双块式无砟轨道结构设计

北京新机场线是我国首条最高速度达160 km/h的地铁线,轨道结构采用双块式无砟轨道,高架地段首次采用取消底座结构设计,为了保证轨道结构的安全可靠,有必要对无砟轨道道床结构进行结构选型及配筋设计。通过建立高架地段无砟轨道结构的有限元模型,对道床板板长、板宽、板厚进行了选型分析。针对无砟轨道无底座设计方案,考虑了列车荷载、温度梯度、桥梁挠曲3种主要荷载类型,提出了荷载组合方案,研究其关键控制因素,对道床板进行了配筋设计及检算。通过参数比选,完成了道床板的尺寸参数选择;在3种荷载类型中,温度梯度在道床板中引起的弯矩值最大,在设计荷载中占据主导因素,合理减小道床截面高度可有效降低温度梯度作用;道床板配筋应以控制裂缝为原则进行设计。

Structural Design of Double-block Ballastless Track in Elevated Bridge Section of Beijing New Airport Line

Beijing New Airport Line with the maximum speed of 160 km/h is the first subway line in China. Double-block ballastless track structure is used, and the base structure is cancelled the first time in the elevated section. In order to ensure the safety and reliability of track structure, it is necessary to carry out structural form selection and reinforcement design. In this paper, a finite element model is established to conduct lectotype analysis on the length, width and thickness of track slab, and such main loads as train load, temperature gradient and bridge deflection are taken into consideration. The loading combination method is proposed, key control factors are analyzed and then reinforcement design and check calculation of track slab are carried out. Through parameter comparison, the dimension parameters of track slab are determined. Temperature gradient is the dominant factor of the three loads because the moment caused by temperature gradient is the largest. Thus the influence of temperature gradient can be lowered effectively by reducing the cross section height of track slab. The reinforcement of track slab should be designed with focus on crack control.