高速列车荷载作用下无砟轨道地基竖向耦合动力响应研究

建立高速列车荷载作用下车辆系统-无砟轨道-地基耦合动力模型,通过Fourier变换求解弹性半空间地基土体的动力控制方程,同时根据轨道底座与半空间的接触条件得到了弹性半空间表面竖向位移在频域内的表达式,再采用快速Fourier 变换求得了时域内的土体位移解。结合算例,分析了列车速度、轨道结构参数等因素对地基动力响应的影响。研究结果表明:板下调整层弹簧刚度系数越大,地基土动力响应越大,地表振动越大;底座弯曲刚度越大,地基土动力响应越小;随着列车速度增加,地基土动力响应增大;距离轨道中心处越远,地基土动力响应越小。

STUDY ON VERTICAL DYNAMIC RESPONSE OF BALLASTLESS TRACK AND SUBGRADE OF HIGH-SPEED TRAIN LOADS

A dynamic model for a vehicle system,ballastless track and subgrade subjected to a moving train load is developed.By means of Fourier transform,the dynamic fundamental equations for an elastic half space are solved.The vertical displacement of the subgrade is obtained by using the contact condition between the track and a half space.The dynamic displacement of subgrade in time domain is obtained by using the Inverse Fast Fourier Transform.Through numerical examples,the variation characteristics of dynamic response of the subgrade are studied by introducing the different train speed,track stiffness and other parameters.It is shown that the amplitude of dynamic response increases with the increasing train speed,and decreases gradually with the increasing distance away from the track center along the longitudinal and vertical directions.It is also found that the rail stiffness has the most influence on the foundation dynamic response,the orbital plate stiffness takes the second place and base stiffness is in the last place.And the bend stiffness coefficient of the base is more important than other parameters in the analysis of the foundation dynamic response.