列车荷载与水耦合作用下无砟轨道伤损机理研究

The non-ballasted track had been widely used with the massive construction of the high-speed railway in China. The damage issue of non-ballasted track mainly based on the flaw was becoming gradually evident, especially the influence of rainwater to the damages. Nowadays there was a lack of the systematic research on the relevant problems at home and abroad. This project aimed at the water-containing crack propagation issue among the typical damages of the ballastless track to research on the development mechanism of the concrete damage under the action of the complex high-speed dynamic train load and water invasion theoretically and experimentally. The wheel-rail coupling dynamics theory was applied to analyze the action characteristics of the high-speed dynamic train load including amplitude and frequency. With the simulated dynamic train load acting, the dynamic water pressure test and crack development test for the damaged concrete were conducted to analyze the action characteristics of the dynamic water pressure and the crack development properties. With consideration of the calculation theory on the concrete fatigue crack propagation, the fracture mechanics and fluid-solid coupling theory were applied to establishing the calculation theory and method about the force and transformation of the damaged water-containing concrete under the coupling action of the dynamic load and water in order to research on the development mechanism of the damages in the concrete structures like crack and the influencing properties of the relevant factors. The research achievements provided reference for enriching and perfecting the theory on the concrete damages.

无砟轨道伴随我国高速铁路大规模修建得到了广泛应用，但以裂纹为主要形式的伤损问题也逐步凸显，特别是雨水对伤损的影响尤为突出，目前国内外对相关问题还缺乏系统研究。本项目拟针对典型无砟轨道伤损中的含水裂纹扩展问题，对高速列车复杂动荷载作用及雨水侵入条件下，混凝土的伤损发展机理进行理论与试验研究。应用轮轨系统耦合动力学理论，研究高速列车动荷载的幅值及频率等作用特征；通过施加模拟列车动荷载，进行伤损混凝土动水压力试验和裂纹扩展试验，研究动水压力的作用特性及裂纹扩展性态；应用断裂力学和流固耦合理论，结合混凝土疲劳裂缝扩展计算理论，建立动荷载与水耦合作用下含水伤损混凝土的受力与变形计算理论和方法，研究混凝土结构中裂缝等伤损的发展机理和相关因素的影响特性。研究成果将为进一步丰富和完善混凝土伤损理论提供参考。

无砟轨道伴随我国高速铁路大规模修建得到了广泛的应用，但以裂纹为主要形式的损伤问题也逐步凸显，特别是雨水丰富和排水不畅地区，对损伤的影响尤为突出。本项目针对典型无砟轨道损伤中的含水裂纹扩展问题，对高速列车复杂动荷载作用及雨水侵入条件下，裂纹的发展机理进行理论与试验研究。通过现场调研，明确无砟轨道的水病害特征，并提出无砟轨道水致损伤的关键科学问题和计算方法。基于轮轨耦合系统动力学理论，建立列车-无砟轨道耦合动力计算模型。开展轮轨力、轨道结构动力响应现场测试，并结合理论研究成果，明确轨道垂向受力分布特征。为进一步开展动水压力及无砟轨道水致损伤提供加载条件。基于质量守恒、动量定理，采用控制体积法导出列车荷载作用下无砟轨道层间裂纹内动水压力分布解析式。开展层间裂纹内动水压力模型试验，验证理论分析的正确性。开展无砟轨道层间裂纹内动水压力分析，明确动水压力产生与变化机理，为裂纹扩展研究提供水压力边界条件。开展层间力学性能试验，获取界面粘结参数，为评估列车荷载与水耦合作用下的无砟轨道层间裂纹扩展状态提供判断依据。以轨道垂向受力特性和动水压力分布特性研究阶段的成果作为列车荷载与水耦合作用下的无砟轨道裂纹扩展的边界条件，建立列车荷载与水耦合作用下的无砟轨道裂纹扩展预估模型，计算裂纹尖端的应力和应力强度因子。根据层间粘结强度，对高速列车荷载与水耦合作用下的无砟轨道层间裂纹的安全性进行评估，明确无砟轨道的裂纹发展机理，并提出轨道安全预警标准。研究成果将为进一步丰富和完善混凝土损伤理论及无砟轨道的养护维修提供理论依据。