Abstract: Aiming at the structure of double-block ballastless track, a Winkler foundation composite beam analytical model was established to predict the bending deformation of the track during uneven settlement of a concave-cosine soil subgrade. And by comparing and verifying the beam body finite element model considering the nonlinear contact between the track and subgrade, the critical conditions applicable to the Winkler foundation composite beam model for predicting track deformation, namely the critical conditions triggered by the nonlinear contact between the track and subgrade, were determined. The research shows that under the condition of small settlement amplitude/wavelength, the predicted results of the two models are in good agreement. While, under the condition of large settlement amplitude/wavelength, the predication results of rail deformation of the analytical model are larger. The finite element simulation results of the beam body show that there is a significant void phenomenon between the track and the roadbed, with a contact stress of 0. The critical conditions triggered by the nonlinear contact between the track and subgrade are given, that is, when the wavelength of uneven settlement is 10, 15, 20, 25 m, the critical settlement amplitude of Winkler foundation composite beam model is 1, 3, 10, 30 mm respectively, and when it is greater than the critical settlement amplitude, the contact nonlinearity between the track and the roadbed begins to trigger. The settlement wavelength-critical settlement amplitude curve of Winkler foundation composite beam is obtained, which provides theoretical basis and calculation method for rapid and accurate prediction of rail surface deformation under uneven settlement conditions of the subgrade.

Key words: geotechnical engineering; Winkler foundation; ballastless track; subgrade settlement; rail deformation; composite beam

摘要： 针对双块式无砟轨道建立Winkler地基叠合梁解析模型，用来预测下凹余弦型土质路基不均匀沉降时轨道的弯曲变形，并采用考虑轨道-路基接触非线性的梁-体有限元模型对比验证，确定出了Winkler地基叠合梁模型预测轨道变形适用的临界条件，即轨道与路基接触非线性触发的临界条件。研究发现：小沉降幅值/波长工况下，2种模型预测结果吻合得很好，而较大沉降幅值/波长工况下，解析模型预测轨道变形结果偏大，梁-体有限元模拟结果显示轨道与路基间发生了明显的脱空现象，接触应力为0；给出了轨道与路基接触非线性触发的临界条件，即路基不均匀沉降波长为10、15、20、25 m时，Winkler地基叠合梁模型应用的临界沉降幅值分别为1、3、10、30 mm，大于临界沉降幅值时，轨道与路基接触非线性开始触发；得到了Winkler地基叠合梁沉降波长-临界沉降幅值曲线，为快速准确预测路基不均匀沉降工况下的轨面变形提供了理论依据和计算方法。

关键词: 岩土工程；Winkler地基；无砟轨道；路基沉降；轨面变形；叠合梁