Mud pumping in subgrade beds under ballastless tracks will deteriorate the dynamic performance of infrastructure under railway lines,reduce the smoothness of the railway lines,and seriously affect the comfort and safe...Mud pumping in subgrade beds under ballastless tracks will deteriorate the dynamic performance of infrastructure under railway lines,reduce the smoothness of the railway lines,and seriously affect the comfort and safety of the trains.Due to their good mechanical properties,twocomponent polyurethane materials can be used for grouting to treat the fouling problems caused by ballastless track mud pumping.To develop a polyurethane formula suitable for the treatment of ballastless track mud pumping,we first performed indoor experiments to investigate the mechanical properties and gelation time of polyurethane elastomers synthesized with different raw material composition ratios,to determine an optimal composition ratio of the raw materials.Then,we conducted a dynamic field test to verify the remediation effect of the polyurethane material fabricated according to the design ratio.The results showed that polyurethane grouting material with the selected design ratios improved the contact characteristics between the surface layer of the subgrade bed and the base plate in the area,coordinating the dynamic response between the track structure and the subgrade bed.Thus,the obtained polyurethane grouting material could be used to renovate mud pumping areas of ballastless tracks with a good treatment effect.展开更多
Two-component submonolayer growth on triangular lattice is qualitatively studied by kinetic Monte Carlo techniques.The hopping barrier governing surface diffusion of the atoms is estimated using pair interaction poten...Two-component submonolayer growth on triangular lattice is qualitatively studied by kinetic Monte Carlo techniques.The hopping barrier governing surface diffusion of the atoms is estimated using pair interaction potentials.Several degrees of freedoms enhancing the surface diffusion of atoms are also introduced.The main advantages of the presented technique are the reduced number of free parameters and the clear diffusion activated mechanism for the segregation of different types of atoms.The potential of this method is exemplified by reproducing(i)phase-boundary creation and dynamics related to vacancies and stacking faults;(ii)a special co-deposition and segregation process where the segregated atoms of the second component surround the islands formed by the first type of atoms.展开更多
基金The authors gratefully acknowledge the financial support for this research by the National Natural Science Foundation of China(Grant Nos.51978588 and 52078434)。
文摘Mud pumping in subgrade beds under ballastless tracks will deteriorate the dynamic performance of infrastructure under railway lines,reduce the smoothness of the railway lines,and seriously affect the comfort and safety of the trains.Due to their good mechanical properties,twocomponent polyurethane materials can be used for grouting to treat the fouling problems caused by ballastless track mud pumping.To develop a polyurethane formula suitable for the treatment of ballastless track mud pumping,we first performed indoor experiments to investigate the mechanical properties and gelation time of polyurethane elastomers synthesized with different raw material composition ratios,to determine an optimal composition ratio of the raw materials.Then,we conducted a dynamic field test to verify the remediation effect of the polyurethane material fabricated according to the design ratio.The results showed that polyurethane grouting material with the selected design ratios improved the contact characteristics between the surface layer of the subgrade bed and the base plate in the area,coordinating the dynamic response between the track structure and the subgrade bed.Thus,the obtained polyurethane grouting material could be used to renovate mud pumping areas of ballastless tracks with a good treatment effect.
基金the Hungarian National Science Foundation under contract No.OTKA T048699INNOVATIAL 6th Framework Program Project IP 515844-21 and by Romanian CNCSIS 41/183 and CEEX/Nanobiospec grant.
文摘Two-component submonolayer growth on triangular lattice is qualitatively studied by kinetic Monte Carlo techniques.The hopping barrier governing surface diffusion of the atoms is estimated using pair interaction potentials.Several degrees of freedoms enhancing the surface diffusion of atoms are also introduced.The main advantages of the presented technique are the reduced number of free parameters and the clear diffusion activated mechanism for the segregation of different types of atoms.The potential of this method is exemplified by reproducing(i)phase-boundary creation and dynamics related to vacancies and stacking faults;(ii)a special co-deposition and segregation process where the segregated atoms of the second component surround the islands formed by the first type of atoms.
