Vibration Characteristics Of High-speed Railway Subgrade And Vibration Isolation Analysis Of Wave Impedance Block In Cold Region

In recent years,the high-speed progress of China's railways has developed rapidly,which brings about a tremendous impact on people's work and daily life as the running of high-speed trains causes vibration problems along the lines.Given a large number of existing railway lines pass through cold regions in China,the difference of propagation and attenuation of vibration waves caused by high-speed trains between cold-region soils and normal-temperature soils must be considered.The destructive effect of moving railway loads on frozen subgrade is even more pronounced.Revealing this kind of moving track load damage to frozen soil is not only an important guarantee for ensuring high-speed railway operation and maintenance safety in cold regions,but also an important cornerstone for the prevention of environmental vibration caused by moving railway load in cold regions.Based on this situation,this paper studied the vibration characteristics and vibration isolation technology of high-speed railways in cold regions and carried out the following work using numerical analysis and theoretical analysis methods.A three-dimensional high-speed railway track-subgrade dynamic coupling numerical model was established based on ABAQUS software.The section structure,the constitution of frozen soil material and the contact characteristics of three-dimensional track-frozen soil-pile system were analyzed.The influence laws of the coupled system were compared with the measured results,thereby the optimized three-dimensional dynamic coupled finite element model was established.Based on the three-dimensional dynamic coupling numerical model,the vibration characteristics of the roadbed and the vibration isolation performance of the WIB were analyzed.The results showed that the vibration behind the board has obvious attenuation after vibration isolation,which illustrated the WIB has a great vibration isolation effect.The control law of WIB material parameters to control the vibration isolation effect was systematically studied such as elastic modulus,width,length,height(buried depth),damping ratio and layout position etc.The result showed that the vibration-isolating effect is enhanced when the elastic modulus of the WIB increases within a range bigger than the dynamic elastic modulus of the soil;Vibration isolation effect is amplified with the increase of the design width and design height of the WIB;Vibration isolation effectincreases near the back part of the block with the decrease of the buried distance of the WIB,while obviously attenuated in distant locations;Improvement of vibration isolation is not obvious when the damping ratio of the WIB changes within the actual value range;The vibration-isolating effect improves significantly after a reasonable optimization to the design parameters of WIB refer to the above conclusions,which proves the feasibility of WIB vibration isolation.The influence of speed,season and temperature changes on the effect of vibration isolation was studied systematically.The results showed that the vibration isolation effect is more obvious when the speed of high-speed trains increases within a certain range;When the negative environment temperature is low in the freezing process of soil in early winter,the soil vibration is strong,but the vibration isolation effect is relatively good;When melting layer volume increases in the melting process of soil during spring thawing period,the initial vibration of the subgrade soil is weakened as well as the vibration isolation effect.