摘要
利用2.5维有限单元方法研究高速列车荷载引起的非饱和路基地面振动。视轨道结构为非饱和地基上的Euler梁。对控制方程进行时间Fourier变换和轨道方向波数变换,结合边界条件和Galerkin法推导出频域内2.5维有限元方程,将空间三维问题化为平面上的两维问题。分析了车速和路基饱和度对地面振动及超静孔隙水压力的影响。结果表明,同一车速下,非饱和路基地面振动加速度幅值大于饱和路基。随车速增大,饱和路基地面加速度幅值减小,非饱和路基则先剧烈减小后稍有增大。饱和路基地面振动加速度主频率随车速增大几乎不变小(均为2.2 Hz),而对非饱和路基则是先减小后增大。地面振动加速度在低速时随距轨道中心距离快速衰减,高速时衰减很慢。地面振动加速度可能会出现反弹增大现象,其出现及位置与车速密切相关。同一车速下路基超静孔隙水压力峰值随路基饱和度下降急剧减小,超静孔隙水压力分布深度在0~4.5 m,幅值约在1.8 m深度。
A two-and-a-half-dimensional finite element model(2.5D FEM)was used to investigate surface vibration of the unsaturated ground subjected to moving loads caused by high-speed trains.The track structure was simplified as an Euler beam resting on an unsaturated porous half-space.The governor equations in frequency domain was derived by applying the Fourier transform with respect to time,and 2.5D finite element equations for unsaturated ground were then established using Galerkin method and wave-number transform in the load moving direction.The three-dimensional(3D)dynamic problem was reduced to a two-dimension alone.Influences of train speed and water saturation of unsaturated subgrade on its vertical ground vibration and the excess pore water pressure are analyzed.Result shows that:the amplitude of the ground vibration acceleration of unsaturated subgrade is larger than that of saturated subgrade at the same speed.As the speed increases,the ground acceleration amplitude of saturated subgrade decreases,while of the unsaturated subgrade it decreases and then increases slightly.The dominant frequency of ground vibration acceleration of saturated subgrade varies little as train speed incenses(about 2.2 Hz),while of unsaturated subgrade the dominant frequency decreases and then increases with the train speed increasing.The ground vibration acceleration attenuates rapidly at low speed while slowly at high speed with the distance from track center.Ground vibration acceleration rebound zone may occur,and its location is strongly related to the train speed.The excess pore water pressure is mainly distributed within 4.5 m below the ground and decreases sharply as the water saturation decreases,and the peak value appears at about 1.8 m beneath the ground surface.
作者
高广运
姚哨峰
孙雨明
GAO Guangyun;YAO Shaofeng;SUN Yuming(Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;College of Urban Construction and Safety Engineering,Shanghai Institute of Technology,Shanghai 201418,China)
出处
《地震工程与工程振动》
CSCD
北大核心
2019年第5期28-39,共12页
Earthquake Engineering and Engineering Dynamics
基金
国家自然科学基金项目(41772288)~~
