纵连式无砟轨道板-砂浆层层间混合模式开裂分析方法与机理研究

Longitudinal continuous slab track is mainly composed of track slab, mortar layer and base layer. As laminated composite materials, the interface is weak. Delamination, especially interface cracking between slab and mortar layer, is prominent. Due to the characteristics of multi-layer structure and complex load, the interface cracking is not purely tensile or shear cracking, but a typical mixed-mode cracking. In order to solve the problem of interface damage, it is necessary to study the mechanism of mixed-mode interface cracking at first. The existing push slab test (pure shear) and uplift slab test (pure tensile) are hard to meet the research needs. And the existing models of interface disease of slab track have some problems, such as the stress oscillation of crack tip and self-repairing, which could not simulate mixed mode of interface crack accurately. This project makes an in-depth study of the constitutive model and parameters of mixed-mode interface cracking base on the theoretical analysis, the indoor model test and field test. The multiscale method is used to establish the finite element model of mixed-mode interface cracking of longitudinally coupled slab track. Base on the proposed model, the mechanical behavior and deformation mechanism of ballastless track system and the cracking mechanism among layers under complex load are systematically studied. The influence mechanism of ballastless track interface disease on service performance of track system is also analyzed. Through the research of this project, the analysis method of mixed-mode interface cracking between longitudinal continuous ballastless track slab and mortar layer is proposed to reveal the mechanism of interface cracking, and provide theoretical support for the disease treatment of ballastless track.

纵连板式无砟轨道主要由轨道板、砂浆层、支承层等组成，如同层合复合材料一般，层间结合较弱。分层病害，尤其是轨道板-砂浆层层间开裂，较为突出。由于轨道的多层结构特征和复杂荷载作用，层间开裂并非单纯的张拉或剪切开裂，而是典型的混合模式开裂。为了解决层间病害问题，非常有必要首先对轨道层间混合模式开裂机理进行研究。目前既有的推板试验（纯剪）和揭板试验（纯拉）难以满足研究需要，而既有理论模型又存在裂尖应力振荡和“自修复”等病态问题，无法准确模拟层间混合模式开裂过程。本项目结合理论和室内外试验，深入研究层间混合模式开裂本构模型和参数；建立纵连板式无砟轨道层间混合模式开裂分析多尺度有限元模型，系统研究复杂荷载作用下无砟轨道系统力学特性和层间开裂机理，并细致研究层间病害对轨道系统服役性能的影响机制。通过本项目的研究，提出无砟轨道层间混合模式开裂分析方法，揭示层间开裂机理，为无砟轨道病害整治提供理论支撑。

无砟轨道服役状态直接影响行车安全性和平稳性，其纵连板式无砟轨道存在的层间离缝病害问题，将突发上拱大变形危及行车安全，是近几年研究的热点和难点。. 本项目围绕三个关键性的科学问题，从层间混合模式开裂本构模型、无砟轨道层间混合模式开裂分析模型及方法、无砟轨道系统力学行为及层间开裂发生发展机理、层间病害影响及整治等方面开展研究。. 在层间混合模式开裂本构模型方面：通过对既有模型牵引力-分离本构和卸载-再加载本构的改进，提出了改进的内聚力本构，解决了“自修复”和“应力振荡”等问题。. 在无砟轨道层间混合模式开裂分析模型及方法方面：基于UINTER子程序开发了层间混合模式开裂分析模块，采用多尺度建模方法，将无砟轨道宏观模型与细观层间混合模式开裂本构模型相结合，建立了无砟轨道层间混合模式开裂分析模型和方法。. 在无砟轨道系统力学行为及层间开裂发生发展机理方面：揭示了施工阶段轨道板-砂浆层层间开裂机理、无砟轨道主体结构受力变形的参数影响规律；研究了运营阶段列车荷载-温度耦合作用下无砟轨道力学性能。. 在层间病害影响及整治方面：研究了层间病害对纵连板式无砟轨道服役性能影响机制和参数影响规律；揭示了温变荷载下纵连-销钉体系纵向受力行为与细观结构承力特性；提出了无砟轨道预加固植筋方案适应的升温幅度；揭示了纵连板式轨道-销钉体系动力响应及参数影响规律。. 本项目在执行期内，共发表论文12篇，申请发明专利5项，培养硕士研究生6名，参加国际学术会议3次，参编标准2部，所获成果远超项目预期。无砟轨道层间病害分析方法、损伤机理和整治措施方面研究成果，可为无砟轨道层间损伤修复提供理论支撑，为我国高铁安全运营提供保障。