Study On The Uniformity Of The Bearing Rigidity Of Continuously Compacted Subgrade Structure Of Ballastless Tracks

Being as the under part construction of the ballastless tract structures, the status of the characters of the subgrade structure can have a major influence on the dynamic characteristics of the track structures. To meet the requirements that the track can maintain a higher stability, a good uniformity, a higher level of smoothness, and an outstanding saving on the maintenance works, it is demanded that the subgrade, which is under the activation of the dynamic forces, shall have not only a mere deformation, higher stability, but also a good uniformity of the bearing rigidity of the subgrade, and therefore, this will then make a higher demand on the quality of the compaction work of subgrade. By adopting a method of the kinetics and control theory, this paper studied the evaluation index and dynamic control mechanism of the continuous compaction of the subgrade of high speed railways. Based on the study for the regularity of the deformation and applied force patterns, which was achieved by setting up a 3-dimensional finite element model of the track slab/subgrade, this paper present a controlling method and standard on the continuous compaction of subgrade, and finally provide a theory support for the testing and control process of the continuous compaction of ballastless track subgrade of high speed railways. The major study contents and relevant conclusions are listed below:1. Study on the characters of status and the method of expression during the formation process of compaction of subgrade. Through a study on the relationship between the elastoplastic deformation and the reaction force of the subgrade structure, a critical variable to represent the status of the subgrade structure in the process of compaction was selected; Furthermore, through a study on the relationship between the status variable and the changes of the compaction status of the subgrade, this paper choose the reaction force of the subgrade structure, and use it as an index to represent the changes of the compaction status of subgrade.2. Study on the index of kinetics for the compaction status of subgrade. Through the study on the analysis method and the kinetics model, which was used to simulate the interaction between the subgrade and the compaction equipment, and based on the relationship between the dynamic response characters and the compaction status of the subgrade, this paper analyzed the corresponding relationship between the dynamic response of the compaction equipment and the reaction force of the subgrade structures, verified their relationship by test, and set up a modular method of calculation and measurement, capable to produce the information about the reaction force of subgrade.3. Study on the continuous measuring technology and monitoring system. Starting from the principal of measuring technology, the composition of the continuous compaction monitoring system was studied, carried out the analysis and description on the respective characters of the major composition parts, such like the excitation, measurement and processing systems, and further presented the model and requirements of the continuous measuring technology. With reference to the specialty of the railway subgrade works, participated in the development of new "compaction process monitoring system (CPMS)"of research team.4. Study on the dynamic control mechanism of subgrade compactions. Via an analysis made to the affective and controlling factors of the subgrade compaction quality, this paper set up a feedback controlling theory, and studied the vibrating parameters of rolling machines, together with the control mechanisms of the compaction degree and compaction stability, and at the mean time, presented its proof by testing.5. Study on the effect imposed by the uniformity characters of subgrade structures upon to the structure characters of ballastless tracks. By setting up a three-dimensional simulation model of kinetics to represent the structural system of railway track/subgrade, this paper analyzed the change rules of dynamic displacement and dynamic stress of track slabs under different characters status of various subgrade structures. And in order to comply with the requirements on safety and smoothness of the operation of trains, this paper presented the limitation of allowance on non-uniformity of the subgrade structure characters.6. Study on the standard of control to the uniformity characters of continuously compacted subgrade. This paper set up a statistical index system to reflect the discrete degree in the bearing rigidity of subgrade, and by referring the limitation of allowance on non-uniformity of the subgrade structure characters, the paper studied the criteria on joint utilization of the continuous compaction controlling method and the conventional controlling method, proposed a relevant comprehensive controlling method, which was verified through tests. Furthermore, by undertaking a study on the representation form of the non-uniformity of subgrade, this paper finally presented the criterion on the control of uniformity of continuously compacted subgrade.The research work carried out with this paper has revealed comprehensively the rules of effect, which was imposed by the characters status of the continuously compacted subgrade structures, to the characters of the track structures, the paper presented a limitation of allowance on the non-uniformity of subgrade structure characters, and therefore provided a theoretical and technical support to the control and testing of the works of continuously compacted subgrade.