The Key Technology Research Of Concrete Crack Control Of Passenger Dedicated Line In The Northwest

Passenger dedicated line in northwest region was generally used the monolithic track replaces the original ballast bed. The ballastless track is a kind of track structure with high stability, high ride comfort and less maintenance. In northwest China in the construction and operation process of the ballastless track, however, the monolithic track-bed cracking is one of the main problems which affecting its overall quality, while few relatively studies have been conducted. In this paper, based on the scientific research project of Lanzhou Railway Bureau "The key technology development research of northwest railway monolithic track-bed concrete crack control"(ZC-QT-062), the cause of the monolithic track-bed cracks in construction phase and its control measures were studied, the main research content is as follows:1. Combined with the northwest environmental characteristics of gale wind, drought and large temperature gap between day and night and the monolithic track-bed structure with relatively small ratio of its volume and surface area, analyzed the solid concrete causes of large contraction in condensation hardening phase, and on that basis analyzed the reason why northwest monolithic concrete cracks easily.2. The northwest monolithic track-bed site investigation has been made for the concrete cracking, summarized the cracks’ form and development regularity, and the causes of various cracks has carried on the preliminary demonstration from the aspects of the track structure and concrete construction technology. Through contrast analyzed the various cracks form, the main research content of this article was determined.3. Through numerical simulation, the influence of the adopted monolithic track-bed sleeper structure of the concrete stress distribution rule in condensation hardening stage were analyzed, the concrete stress concentration caused by the sleeper angle was the main reason for eight-sharped cracks were pointed out and improvement measures were put forward.4. Combined with the research results and numerical analysis, the method of experiment research in a laboratory was adopted to verify the control measures of the determined eight-sharped crack control measures, including change the sleeper angle into rounded shape, increasing the longitudinal reinforcement or U-shaped steel, improving the plaster way in the sleeper end, etc., and the effects of various measures were demonstrated and analyzed.5. Combined with the above research results, through refer to the information related to monolithic track-bed cracks, the northwest railway solid bed in crack control measures under the influence of different factors were summarized...