路基冻胀下无砟轨道不平顺特征及动力学行为研究

Frost heave of railway subgrade leads to structure damage and track irregularity of the ballastless track, which directly affects the safety and stability of train operation. It is the key factor that leads to the speed reduction of high-speed railway in cold areas. In the current, a large number of researches are focused on the mechanism and control measures of frost heave. On the contrary, few researches have been performed on the mechanical behaviors of ballastless track under frost heave of subgrade. In particular, these studies are relatively rare, such as the relationship between frost heave deformation of subgrade and track irregularity, interlayer gap mechanism of ballastless bed, the dynamic response of vehicle-track in the case of frost heave. Therefore, a series of problems related to track irregularity and dynamic behavior caused by frost heave of subgrade are needed to be solved..Considering the bonding characteristics and failure criterion of ballastless track which composed by multilayer heterostructure, a ballastless track-subgrade spatial coupling model will be developed by combining with microscopic and macroscopic analysis. Using the model, track irregularity of ballastless track and the interlayer gap mechanism of ballastless bed will be studied. Meanwhile, considering the structure diseases in detail, a new dynamic analysis method will be developed to study the dynamic response of vehicle-track system. According to the variation of some sensitive indexes of dynamic parameters, an intelligent recognition method of frost heave deformation of subgrade will be created with neural network method. Finally, considering the durability, safety, comfort and other factors, the control standards of frost heave will be proposed for subgrade of high-speed railway. The research results will be used as a base to design theory and maintenance method of high-speed railway in cold regions.

路基冻胀会导致无砟轨道产生结构破坏和不平顺，直接影响列车的安全、平稳运行，是严寒地区高速铁路冬季降速运营的关键影响因素。既有研究中，针对路基冻胀机理和控制措施等研究较多，对路基冻胀下无砟轨道力学行为的研究相对较少，特别是冻胀与轨道不平顺的关系、无砟道床离缝机理、冻胀下车-轨动力响应等研究相对匮乏。路基冻胀导致的一系列与无砟轨道平顺性、动力特性相关的问题亟待解决。.项目考虑无砟轨道多层异质结构间的粘结特性和破坏准则，建立细观与宏观相结合的无砟轨道-路基分析模型，提出路基冻胀下无砟轨道不平顺特征，揭示无砟道床离缝机理。提出可详细考虑结构病害特征的新型动力分析方法，研究路基冻胀下车辆-无砟轨道的动力学行为。根据动力参数敏感指标变化特征，采用神经网络建立路基冻胀变形的智能识别方法。综合考虑耐久性、安全性及舒适性等因素，提出路基冻胀的控制标准。通过研究，补充完善严寒地区高速铁路设计理论和维护方法。

目前，我国正在东北、西北等季节性冻土地区开展大规模的高速铁路建设。这些高速铁路穿越了冻土广泛分布的高寒地区，面临着路基冻胀问题，掌握季节性冻土地区高速铁路路基冻胀对轨道结构的影响对于优化完善高速铁路的设计、建设及维护措施非常关键。项目针对路基冻胀变形对无砟轨道的影响问题，重点研究冻胀下路基-无砟轨道-轨面间位移传递关系、无砟轨道多层结构间离缝机理及发展规律、冻胀下轨道不平顺特征及其对车辆-轨道系统动力响应的影响等5个方面的内容。研究成果如下：（1）提出用幅值传递比可描述路基-无砟轨道-轨面间位移传递关系，采用在纵向位置上钢轨变形变化率来评价轨道不平顺状态。研究发现：随着冻胀量的增大、冻胀波长的减小，波长传递比逐渐增大。（2）提出利用轨道不平顺波形图、轨道不平顺累积分布和轨道不平顺谱等方法，分析高速铁路路基冻胀及冻融前后轨道不平顺变化规律。研究结果表明：冻胀对路基地段波长10m以上的高低和水平不平顺影响较大，对中长波轨向不平顺稍有影响，对其它影响较小。（3）研究复杂温度荷载作用下自密实-底座板层间离缝变化规律。研究表明，随着冻胀量的不断增大，离缝高度和离缝长度逐渐增大；随着冻胀波长的逐渐增大，离缝高度和离缝长度均呈减小趋势。（4）建立车辆-轨道-冻胀路基精细化空间耦合动力学分析模型，分析了不同路基冻胀条件以及不同运营条件下轮轨相互作用情况。研究发现，轮重减载率对冻胀波长更敏感，车体垂向加速度对冻胀量更敏感，应重点关注冻胀量大于15mm、冻胀波长小于15m路基冻胀地段。（5）利用RBF神经网络模型实现了对路基冻胀波长和冻胀量的初步识别，提出了静、动力学结合的高速铁路路基冻胀控制标准。发表文章30余篇，其中SCI文章6篇、EI文章20篇。培养硕士生9人、博士研究生2人，协助科研团队培养博士研究生4名、博士后2名。授权发明专利4项、软件著作权1项，申请相关专利5项。举办参加国内外重要会议11次，获得科研相关奖励11项。