高速铁路路基不均匀沉降对双块式无砟轨道平顺性的影响

Effect of Uneven Subgrade Settlement in High-Speed Railway on Double-Block Ballastless Track Regularity

摘要: 受土质不均、地下水位变化、近接施工及其他路基病害影响，路基不均匀沉降不可避免。高速铁路路基沉降会导致轨道几何形态恶化，产生轨道不平顺，进而加剧列车与轨道系统的动力相互作用，影响列车运营品质及线路服役质量。对于整体性好、刚度高的双块式无砟轨道，局部路基不均匀沉降可能导致轨道发生非协调性变形，混凝土轨道结构与路基间形成路基支承不连续的“脱空区”。本文提出了一种考虑非线性路基支承的半解析法用于计算局部路基沉降引起的双块式轨道几何不平顺，在此基础上分析了沉降波长和幅值对轨道变形规律的影响。结果表明，路基不均匀沉降极易引起上部结构的非协调变形，使轨道局部失去路基支承，且对于一定的路基沉降波长，沉降幅值的增大会显著加剧轨道几何形态的恶化，随着沉降幅值增大到一定程度，轨道变形最终维持在一个稳定的水平。就沉降引起的轨道不平顺范围而言，较路基不均匀沉降波长呈轻微扩散，且几乎不受沉降幅值的影响。

Abstract: The uneven subgrade settlement is inevitable due to the influence of subgrade disease such as uneven soil quality, variation of underground water level and adjacent construction. The subgrade settlement of high-speed railway will lead to the deterioration of track geometry, resulting in track irregularities, which will further aggravate the dynamic interaction between train and track system. The quality of train operation and the service performance of the railway line are affected as a result. For the double-block ballastless track with superior integrity and high rigidity, uneven subgrade settlement may lead to uncoordinated deformation of the track, and the “hanging area” with discontinuity subgrade support is generated between the concrete track layer and the soil subgrade. A semi-analytical method considering nonlinear subgrade support is proposed to calculate the track irregularity caused by the uneven subgrade settlement, and the influence of the settlement wavelength and the amplitude on the track deflection is analyzed. Results show that the uneven subgrade settlement is prone to cause uncoordinated deformation of the upper structure, resulting in “hanging areas” between the track and the subgrade. For a certain subgrade settlement wavelength, the increase of the settlement amplitude significantly aggravates the deterioration of track geometry. With the increase of the settlement amplitude, the track deflection finally remains at a stable level. In terms of the range of the track deflection caused by the settlement, it is slightly larger than the settlement section and hardly affected by the settlement amplitude.