Three-dimensional Wave Field Simulation Analysis Of Train-excited Soil Layers In Seasonally Frozen Regions

A negative effect accompanying the development of rail transit is the vibration impact of trains on the surrounding environment.The wave velocity structure of seasonal frozen ground during severe cold period is different from that of unfrozen ground,and the propagation law of mechanical wave formed by rail transit in frozen ground needs to be revealed in depth.Field measurement is subject to many restrictions on equipment capabilities,measurement point layout,and railway operation management.Numerical simulation is a powerful supplementary research method.This paper uses the method of combining measured data and numerical simulation to reveal the wave field characteristics of seasonal frozen ground around rail transit in the northeast cold region,and provide a research basis for rail transit line planning in cold regions and the development of vibration and noise reduction technology.The main research contents of the paper are as follows:(1)Sort out the dynamic shear modulus of frozen soil before and after freezing and the law of temperature change,compare the sensitivity of low strain shear modulus of permafrost and seasonal frozen soil to temperature changes;consider different test methods,In the temperature range of-2°C～-20°C,the linear relationship between the low strain shear modulus of the soil and the temperature is obtained by fitting the linear relationship between the low strain shear modulus of the soil and the temperature,which provides the soil dynamics for the numerical simulation of the rail transit vibration problem in the seasonal frozen soil site The law of parameter change.(2)The fitting relationship between the low-strain shear modulus and temperature is introduced into the mathematical model of the site,and a semi-analytical model of the coupled vibration of the train-track-frozen soil layered site is given,and the parameter influence analysis is carried out on the model;The vibration observation data between the Daqing Longfeng wetlands of the Binzhou Railway verifies the reliability of the model.(3)Based on the ground temperature monitoring data in different seasons in Daqing,set the negative temperature conditions of the site under different temperature conditions in the research section;use the low-strain shear model and the temperature relationship to set the mechanical parameters of the site model for each work condition;Simulate and calculate the soil vibration response of the frozen soil site in various working conditions,analyze the propagation law of soil vibration under different seasonal temperature,different vehicle speeds,and different frequency wheel/rail forces,Finally,some new insights have been made on the vibration characteristics of seasonal frozen soil caused by trains.