无砟轨道层间裂缝车致动水冲刷机理研究

In the abundant rain areas, the mud pumping and mortar precipitation between layers has become a typical water disease of ballastless track. The disease is caused by the repeated scour of the pressurized water flow formed by train load after the interlayer material is softened due to immersion. And its destruction mechanism is not clear at present. Selecting the CRTSⅡslab track in the project, a mesoscopic calculation method of CA mortar softened due to immersion was established, and the local submerged material softening test was conducted to determine the evolution law of material mesoscopic features, fit the material softening equation, and solve the basic parameters problem of erosion damage. The analytic expression of the three-dimensional distribution of water velocity in the interfacial crack of composite slab was deduced. The tests were carried out on the distribution characteristics of water velocity in concrete cracks under dynamic load. The fluid-structure interaction model of the ballastless track and water in the crack was established. According to the above theoretical and experimental results, the main controlling factors affecting the velocity distribution of the water flow and its cross effects were determined as well as the water velocity distribution characteristics. And the hydraulic boundary problem of erosion damage was solved. Based on the mesoscopic finite element method and material mesoscopic features, the mesoscopic calculation model of hydraulic scouring between layers of ballastless track was established to determine the exfoliated timing of material surface particles, obtain the relationship between the size of exfoliated particles and the mesoscopic features of materials, and clear the erosion mechanism of ballastless track crack under the dynamic water. The basic theoretical problem of erosion damage of ballastless track will be solved, and then the theory system of water damage of ballastless track will be enriched and improved.

雨水丰富地区，层间冒浆与砂浆析出已成为无砟轨道的一种典型病害。该病害是层间材料浸水软化后，在列车荷载下形成的有压水流反复冲刷所致，目前动水冲刷机理尚不明确。针对CRTSⅡ型板式无砟轨道，提出CA砂浆材料浸水软化细观计算方法，开展局部浸水下材料软化试验，获得材料细观特征演化规律，构建材料浸水软化方程，解决冲刷破坏的基础参数问题。推导层合板层间裂缝内动水流速三维分布解析式，开展动荷载下混凝土裂缝内动水流速分布特性试验，建立无砟轨道与水的流固耦合计算模型，确定影响动水流速分布的控制主因及各因素间的交叉作用关系，明确动水流速分布特性，解决冲刷破坏的水力边界问题。基于细观有限元法和材料细观特征，建立无砟轨道层间动水冲刷细观计算模型，明晰表面颗粒水致脱落时机，建立脱落颗粒粒度与材料细观特征关系，明确无砟轨道层间车致动水冲刷机理，解决无砟轨道冲刷破坏的基础理论问题，进而丰富和完善无砟轨道水病害理论体系。

雨水丰富地区，层间冒浆与砂浆析出已成为无砟轨道的一种典型病害。该病害是层间材料浸水软化后，在列车荷载下形成的有压水流反复冲刷所致，目前动水冲刷机理尚不明确。针对CRTSⅡ型板式无砟轨道层间动水冲刷问题，首先基于Fick扩散定律，建立无砟轨道内湿度场计算模型，采用节点耦合技术，实现了无砟轨道湿度场由施工到服役全过程的预测。基于BET多层吸附理论建立干湿环境下的无砟轨道内孔隙水计算方法，获得层间积水下无砟轨道内孔隙水分布规律。开展局部浸水下材料软化试验，获得材料软化规律，解决冲刷破坏的基础参数问题。基于质量守恒和动量定理，推导出无砟轨道裂缝内动水流速分布解析式。开展动荷载下无砟轨道层间裂缝内动水流速分布特性模型试验，验证了动水流速解析表达式的正确性，同时实现了毫米级裂缝内的动水流速测试。建立无砟轨道与水的流固耦合计算模型，系统分析了列车荷载特征和裂缝几何形态等因素对动水流速分布的影响，明确动水流速分布特性，解决冲刷破坏的水力边界问题。根据裂缝内产生的动水压力和流速分布的时空差异性，分析了动水压力和流速的协同作用模式。开展冒浆颗粒的粒径分布特性试验，获得不同冒浆阶段的颗粒粒径分布规律。基于细观有限元法和材料细观特征，建立无砟轨道层间动水冲刷细观计算模型，明晰表面颗粒水致脱落时机，明确无砟轨道层间车致动水冲刷机理，解决无砟轨道冲刷破坏的基础理论问题，进而丰富和完善无砟轨道水病害理论体系。