复杂荷载条件下桥上纵连无砟道岔损伤机制与服役性能研究

With the setting of sliding layer and hard foam board, the Longitudinally Coupled Slab Track Turnout (LCSTT) has the characteristic of reducing the interaction between bridge and track. So the LCSTT has been widely applied in China, as a representative slab track turnout structure. Slab track is exposed to the complicated environment and thus will produce different damages due to the long term reaction of train loading, temperature loading, foundation deformation etc. There is a lack of research on damage mechanism and service performance of LCSTT on long-span bridges in China, therefore further study is required. .Based on the damage forming reason and its development law (viz. damage mechanism) of the longitudinally coupled slab track, the research is supposed to build a "turnout-slab-girder-pier" static analysis model and a "vehicle-turnout-slab-bridge" dynamic simulation model, with regarding train loading, temperature loading, occasional loading and foundation deformation as the external condition. Then we can validate the theory simulation models and improve parameters using laboratory tests and field tests. The fracture mechanics and damage mechanics are introduced into the theory simulation models, in order to obtain the influence law of damage on the forces and deformations as well as dynamic response (viz. service performance) of LCSTT. In this research, the damage limit values and the maintenance identification index system are put forward according to riding security and quality, which can be theoretical base for researching the damage mechanism and service performance of LCSTT.

桥上纵连无砟道岔通过滑动层、硬泡沫塑料板等部件的设置可显著减少梁轨相互作用，故已作为一种典型无砟道岔结构在我国大量应用。由于无砟轨道一直暴露于复杂的大气环境，受列车荷载、环境温度、基础变形等多种因素长期作用影响，不可避免产生各种伤损。目前国内外对桥上纵连无砟道岔损伤机制与服役性能的研究相对匮乏，亟待针对该课题开展深入研究。.本研究拟将列车荷载、温度荷载、偶然荷载、基础变形组成的复杂荷载作为外部条件，结合纵连无砟轨道伤损形成原因及发展机理（即损伤机制），建立"岔－板－梁－墩"静力分析模型及"车-岔-板-桥"动力学仿真模型，通过室内试验及现场测试验证力学模型，完善参数取值，应用断裂力学和损伤力学将无砟轨道伤损引入仿真模型，获取伤损对桥上无砟道岔受力变形及动力响应的影响（即服役性能），依据行车安全性和平稳性，构建损伤限值及维修判别指标体系，初步建立桥上纵连无砟道岔损伤机制与服役性能的理论基础.

本项目结合无砟轨道系统伤损的现场调研成果，对CRTSⅡ型板式无砟轨道及道岔区水泥乳化沥青砂浆破坏、轨道板与砂浆层离缝、板底脱空、板上拱、扣件胶垫滑滑出等伤损的机理进行了分析。通过试验室进行了砂浆层与混凝土界面粘结性能试验、砂浆层温度疲劳性能试验、砂浆层动水疲劳性能试验等，获取了砂浆的损伤性能特征。.基于有限单元法建立了桥上纵连板式无砟道岔的梁板计算模型，对道岔板与砂浆层层间离缝以及砂浆层与道岔板之间的层间界面关系进行了有效模拟，主要研究了整体温度荷载和温度梯度荷载单独或组合作用下层间离缝对道岔板的限位性能以及道岔结构受力的影响。基于轮轨系统动力学原理，结合车辆-轨道垂向耦合动力学理论，建立了含快修砂浆的车辆-轨道垂向耦合振动模型，研究了快修砂浆对轮轨系统动力性能的影响。通过车辆-CRTSⅡ型板式轨道-桥梁系统垂向耦合振动模型，分析了轨道板上拱的不同上拱矢度和不同上拱弦长对车辆和轨道结构的动力特性的影响。此外，针对遂渝线无砟轨道试验段铺设的板式轨道水泥乳化沥青砂浆层伤损进行了动力测试。.通过理论分析、试验研究，本项目提出了离缝条件下板边离缝宽度、长度的理论限值，及脱空条件下板端脱空长度和板边脱空宽度的理论限值，以及轨道板上拱矢度、上拱弦长的相关限值。