高速铁路无砟轨道—路基变形计算模型的研究

Calculation Model of Ballastless Track and Subgrade Deformation on High Speed Railway

基于高速铁路路基工后沉降产生于地基沉降变形的机理及无砟轨道各结构层间关系的处理,研究高速铁路无砟轨道—路基变形计算模型。以双块式无砟轨道为例,以下部边界分别为地基面和路基面,道床板与支承层间的关系分别按层间接触和层间结合良好考虑,构建不同条件下的无砟轨道—路基变形计算模型。采用ABAQUS软件进行模型的计算,结果表明,下部边界为地基面和层间关系按接触考虑的计算模型能够反映轨道长波不平顺产生于路基变形的机理,计算结果符合双块式无砟轨道实际的结构特点和受力特征;而下部边界为路基面和按层间结合良好构建的无砟轨道—路基变形计算模型,由于支承层直接承受输入的"强制性"变形荷载,改变了无砟轨道适应路基变形的协调关系,从而导致路基变形引起的无砟轨道层间离缝及支承层产生的拉应力计算值过大,不符合双块式无砟轨道的结构设计原理。由此验证了下部边界为地基面及无砟轨道各结构层按层间接触构建无砟轨道—路基变形计算模型的合理性和可靠性。

A calculation model of subgrade deformation on ballastless track for high speed railway is proposed according to the fact that the post-construction settlement of high speed railway subgrade is mainly caused by foundation deformation as well as the bonding relationship between the track layers.Taking double-block ballastless track as an example,we construct the calculation model to simulate different scenarios which include the lower boundary is either the foundation surface or the subgrade surface and the track slab and bearing layer has a contact or a bonding interface.The calculation results obtained from ABAQUS software show that the model with foundation surface as the lower boundary and interlayer contact can reflect how the long-wave irregularity of track caused by subgrade deformation and the structural and mechanical characteristics of double-block ballastless track,while the model with subgrade surface as lower boundary and bonding interlayer interface,for the bearing layer has to withstand the enforced deformation load directly,prevents the ballastless track to accommodate subgrade deformation,resulting in gap between layers and over-expected tensile stress generated by the bearing layer,therefore fails to comply with the design idea of double-block ballastless track.The result further verifies the rationality and reliability of the proposed calculation model with interface between the subgrade and foundation as lower boundary and the assumption that there is interlayer contact rather than bonding between formation layers of the ballastless track.