严寒地区双块式无砟轨道层间界面粘结失效行为及机理研究

In railway section on the subgrade that is under the effect of extreme temperature environment like cold winter,large temperature difference between day and night and so on in severe cold area, the strongly adhesive interface of double-block ballastless track appears serious adhesive failure :the strongly adhesive interface between bed slab and supporting layer produces a separation，which the weakly adhesive interface is also appearing the same fail behavior; a phenomenon that layered slide appears on the weakly adhesive interface between supporting layer and surface layer of subgrade. Through concrete samples' splitting tensile /shear test,this project is intended to grasp the rules why surface roughness, porosity, material strength and other factors affect the mechanical properties of interface and the mode of failure surface. Meanwhile,combined with the theoretical calculation of fracture energy and numerical simulation analysis, we will establish effectively constitutive relations about cohesive zone model on the interface. Besides, by means of the test of model pushing plate, where interfaces are separated, we will master the interlaminar friction property of fracture plane with different surface shapes, roughness and positions. Finally,by using of simulation control test cabin that is in man-made environment, our team will make temperature experiments about orbit model which is under the action of large temperature difference and high temperature gradient,and based on cohesive zone model,we will make numerical simulation analysis about the damage behavior of model’s interface in the experiment. The purpose of it is to reveal behavior rules and mechanism about the cohesive failure of strongly adhesive interface and weakly adhesive interface, which are cooperative working in severe cold area. The research results of this project can further enrich the research methods of unballasted track’s temperature field and interfacial performance, and could provide a theoretical basis for stability design and interface processing of unballasted track.

受严寒地区冬季严寒、昼夜温差大等恶劣温度环境影响，路基段双块式无砟轨道层间的强、弱粘结界面均出现了明显的粘结失效行为：道床板与支承层的强粘结界面产生了离缝，支承层与基床表层的弱粘结界面出现了分层滑动现象。本课题拟通过试块劈拉/剪切试验，掌握表面粗糙度、孔隙率和材料强度等多种因素对层间界面力学性能、破裂面形态的影响规律，结合试验的断裂能推算和数值仿真分析，建立有效的界面黏聚力模型本构关系。通过界面分离的模型推板试验，掌握表面形状、粗糙度及其所在位置不同的破裂面的层间摩擦性能。利用人工环境模拟控制试验舱，开展大温差、高温度梯度作用下轨道模型的温度试验，并且基于界面黏聚力模型对试验中模型的层间界面损伤行为进行数值仿真分析，进而揭示严寒地区协同工作的强、弱粘结界面粘结失效行为规律及其机理。本项目的研究成果可以丰富无砟轨道温度场和界面性能的研究方法，为无砟轨道的稳定性设计和界面处理提供理论基础。

受严寒地区冬季严寒、昼夜温差大等恶劣温度环境影响，路基段双块式无砟轨道层间的强、弱粘结界面均出现了明显的粘结失效行为：道床板与支承层的强粘结界面产生了离缝，支承层与基床表层的弱粘结界面出现了分层滑动现象，为明确无砟轨道各结构层层间界面性能，保障轨道结构的整体性，本课题针对严寒地区双块式无砟轨道层间界面粘结失效行为及机理展开了研究。. 道床板与支承层之间的层间力学性能及其黏聚力模型的本构关系是本课题研究的主要内容之一，通过开展了室内大量的试块劈拉/剪切试验和室外的推板试验等，明确了表面粗糙度、孔隙率和材料强度等多种因素对层间界面力学性能、破裂面形态的影响规律，掌握了道床板与支承层间接触界面粘结、摩阻性能的主要数值范围，为后续进一步开展轨道结构设计研究/优化补充了试验依据。利用人工环境模拟控制试验舱，开展了大温差、高温度梯度作用下轨道模型的温度试验，研究发现单元轨道板/道床板在日温差变化中板端部分承受的温度荷载幅值要高于板中部分6-7 ℃，并掌握了严寒地区剧烈温度变化环境下无砟轨道温度场的特性，揭示了严寒地区协同工作的强、弱粘结界面粘结失效行为的力学机理和行为规律。课题研究中还通过建立和不断修正接触界面的黏聚力模型，对轨道结构的温度试验成果进行了分析和论证。此外，为保证轨道结构的正常工作状态，强化轨道结构的稳定性，研究并提出了推荐板间横向均匀设置7根直径30mm的传力杆和板中采用销钉强化轨道结构层间连接的工程应用建议。. 本课题共发表科研论文11篇，专利3项，指导学生科创课题10项、本科毕业论文24篇。本项目的研究成果丰富了无砟轨道温度场和界面性能的研究方法，为无砟轨道的稳定性设计和界面处理提供了理论依据，提高了双块式无砟轨道及其相似结构在占我国陆域面积60%以上的严寒和寒冷地区的适应能力。