Study On Settlement Of Railway Ballasted Track And Growth Forecast Of Track Vertical Profile Irregularity

With the development of high-speed and heavy railways, ballasted tracks endure more vibration and impact. Under this condition, track deterioration speed quickens and track maintenance workload increases. But the time for maintenance becomes more and more few. Thus, the contradiction between transportation and maintenance appears. It is an important problem that how solves this contradiction well for railway track management. These are the tendency and requests for time development to understand and master track states and change laws of track states promptly and to work out a set of management system. The management system can help to deal with above contradiction well. However, regardless of the basic theory research or studies on development and application of management information system, there are large gaps existing among home and overseas whose railways have developed. Therefore, it is very significant to commence instantaneously the basic study on track maintenance and management under the condition that the fast and high-speed railways develop vigorously at home.This thesis briefly reviews the domestic and abroad railway maintenance and management survey, the basic theory research and the exploitation of information system for track management, the history and the current situation of the vehicle-track coupled dynamics. On the basis of above studies, directed at the dynamic reciprocity between railway vehicle, track and track base, the thesis proposes the following research thinking that the vehicle-track coupled vibration system and track settlement are combined, regarding the vehicle dynamics, the track dynamics and the track settlement law as foundations, the track settlement due to moving loads of railway vehicles and the dynamic changes of track irregularity can be studied by numerical simulation method. The track settlement model and the vehicle-track coupled dynamics model are the bases for studies on track accumulative settlement and growth forecast of track irregularity. So the existing track settlement models at home and abroad are summarized and analyzed to lay the foundation for selecting appropriate models for simulation. The growth of track irregularity is one of important methods to evaluate track settlement deterioration. On the basis of describing the meanings, classify and characteristic of track irregularity, the research survey and the existing problems about management standards and growth forecast of track irregularity are summarized. And on the basis of summarizing the methods for track irregularity growth forecast at home and abroad, the growth forecast model for track vertical profile irregularity is proposed. The model is established based on the relationship between track settlement and track vertical profile irregularity growth.The vertical vehicle-track coupled dynamics model considering secondary suspension is established based on the vehicle-track coupled dynamics theory. In this model, the track is modeled as a beam laid on three layer supports which are elastic and discrete. The track model can display the effect of local dynamic irregularity such as ballast hardening, sleeper hanging on track vibrations. By simulation examples, the vehicle-track coupled dynamics model and the simulation program are validated.Based on the dynamic data of track irregularity inspected by track inspection railcar on the K80+000～K160+000 Jing-Guang railway line, applying the statistics method, the detailed statistic analyses on track irregularity are done. The probability distribution characteristic of track irregularity is investigated taking the track vertical profile irregularity as example. The correlativity of section maximum and section standard deviation of track irregularity is studied. The influences of different section lengths on the correlativity of section maximum and section standard deviation of track irregularity are also discussed. The actual track irregularity growth laws are presented using the inspected irregularity data. The influences of track structure conditions, railway base conditions and railway operation conditions on irregularity states, irregularity probability distributions and changes of irregularity probability distribution are analyzed. On the basis of above statistic analyses, the statistic forecast methods based on the probability distribution characteristic of track irregularity are discussed, the forecast feasibility and reliability are validated by comparing forecast values with inspected data. The forecast effect and forecast precision of different statistic forecast models of irregularity growth are compared, and the application of the situation transition probability matrix method in irregularity growth forecast is also discussed. Based on the actual growth laws of track irregularity, the long-time growth forecast model of track state is estabished. By examples, the forecast feasibility of above model is analyzed.Applying the research method of track dynamic settlement, by combining the vehicle-track coupled dynamics model, the track settlement model and the irregularity growth model, the simulation program is compiled. Using the program, the dynamic settlement characteristic of ballasted track is analyzed, and the main effect parameters of track settlement are also discussed. The proposal is put forward that track settlement deformation should be considered in the structure design of railway ballasted track.There is a certain relationship between track accumulative settlement and track irregularity growth. By taking the track parameters and transportation conditions of existing railway main line as simulation parameters, using above simulation program, the actual growth state and the growth law of track vertical profile irregularity of existing railway main line are analyzed and compared with the actual inspection data. By comparing, the forecast feasibility of track vertical profile irregularity growth by simulation is validated.