Study On The Flow And Diffusion Behavior Of CRTS Ⅲ Ballastless Track Interlayer Materials

The self-compacting concrete layer is an important part of the CRTS Ⅲ ballastless track structure,and its grouting quality has an important impact on the irregularity and durability of the track.The gap will not only affect the durability of the track structure,but also affect the mechanical properties of the track structure and the running vehicle,and should be repaired in time to prevent the gap from endangering the smoothness and safety of driving.Taking CRTS Ⅲ ballastless track interlayer filling and interlayer repair as the engineering background,on the basis of the commonly used selfcompacting concrete ratio of the layer filling and the common cement repair mortar ratio of the gap repairing,using the VOF(Volume of Fluid)model in the CFD software Fluent,The flow and diffusion behavior of CRTS Ⅲ ballastless orbital interlayer material is regarded as the process of a single homogeneous fluid characterized by the Bingham model flowing into the interlayer and extruding the air between the layers,the main work is as follows:A suitable rheological system was selected to conduct rheometer tests on selfcompacting concrete and cement slurry to obtain their rheological parameters.The slump cylinders of self-compacting concrete and the cement slurry was modeled in equal proportions,inputting rheological parameters to simulate and comparing the numerical results with test results to verify the correctness of the model.Different rheological parameters test groups were set up,and the volume filling rate,inlet velocity,top surface,bottom surface full slurry rate,buoyancy and sinking force were selected as indicators,and the influence of rheological parameters on the flow and diffusion behavior of self-compacting concrete in the filling layer was explored by the self-compacting concrete filling layer grouting model.It is found that the volume filling rate and buoyancy as the key indicators play a crucial role in the selection of the material parameters of self-compacting concrete.As far as the rheological parameters simulation results are concerned,the self-compacting concrete with too little plastic viscosity will produce a large buoyancy force,and the excessive plastic viscosity will reduce the track filling rate and filling efficiency.The yield stress has a significant impact on the track filling rate and should not be excessiveThe test group with different rheological parameters,exhaust pipe spacing and grouting tube burial depth was set,and the grouting volume,inlet velocity,diffusion radius and edge banding side pressure were selected as indicators to study the effects of various variables on the flow and diffusion behavior of cement slurry in interlayer separations.The study found that the pressure suddenly increased after the cement overflows,and it was very easy to cause the failure of the edge banding to lead to repair failure,and the process of stopping the grouting should be strictly observed in the process of gap repairing.Usually,a larger diffusion radius represents a better grouting effect,and in order to achieve a full grouting effect of the gap,a larger plastic viscosity and yield stress should be adopted.The larger the spacing of the exhaust pipes and the deeper the burial depth of the grouting pipes,the theoretically increase the filling rate,but as the spacing of the exhaust pipes increases,the side pressure doubles and the probability of edge failure increases.The larger the depth of the grouting tube,the smaller the inlet velocity and the lower the grouting efficiency.In this paper,the flow pattern of cement repair mortar between layers is simplified and two conditions should be met to ensure the grouting quality,which can be estimated or tested for the reasonable spacing of the exhaust pipe and the burial depth of the grout pipe during the repair of the gap.There are 79 figures,13 tables and 96 references.