土质路基板式无砟轨道基床动力特性研究

Study on Dynamic Characteristics of Soil Subgrade Bed for slab Ballastless Track

无砟轨道技术在高速铁路发展中得到越来越多的应用,在使用温克勒(Winkler)模型对土质路基无砟轨道进行分析时,路基中动应力的分布规律和基床反力系数的取值是决定线路结构设计成败的关键因素。以遂渝线无砟轨道铁路为背景,通过室内大比例动力模型试验,研究了循环荷载下路基基床动态参数的分布特征。考虑到工程实用性,对板式无砟轨道基础板底面的动应力进行必要的简化,联合Odemark理论和弹性理论来计算路基动应力,所得计算值和实测值很接近。在动应力分布已知的前提下,将路基各土层假设为一维压缩模型,并确定合理的有限压缩层厚度,探讨将多土层体系转换为等效Winkler地基模型的方法,得到不同工况下路基的基床反力系数,经与实测值相比较,证实了此计算方法是有效的。

Ballastless track technology is widely being used for the development of high-speed railway. When using Winkler model to analyze the ballastless track on soil subgrade, the dynamic stress distribution rule in subgrade and the subgrade reaction coefficient are the two key factors to dominate success or failure of raitway route structure design. In order to study the distribution characteristics of dynamic parameters in subgrade bed under the action of cyclic load, a large-scale laboratory dynamic model test was performed based on the example of ballastless track of the Suining-Chongqing high-speed railway. Furthermore, in view of engineering applicability, the distribution of dynamic stress of foundation slab bottom of ballastless track was simplified, and the dynamic stress in subgrade was calculated by combining Odemark theory with elastic theory, with the result that the calculated values were very close to the measured data. Then, on the premise that the dynamic stress had been known, this paper assumed each soil layer of subgrade to be one-dimensional compression model, and determined the reasonable thickness of finite compression layer. Then, this paper explored the method of transforming the multiple soil layer system into the equivalent Winkler foundation model, and the subgrade reaction coefficients with different working conditions were acquired. Finally, by comparison with measured data, it is proved that this calculation method is effective.