地震荷载和列车荷载共同作用下弹性均质路基的动力响应

Dynamic response of elastic homogenous subgrade under the interaction of seismic load and railway moving load

为了研究地震发生时列车移动荷载引起的弹性均质路基的振动响应规律,采用ABAQUS软件并与FORTRAN相结合建立轨道结构-路基-地基三维数值计算模型,通过编制DLOAD子程序模拟列车移动荷载,在模型底部输入地震加速度模拟地震荷载,采用三维黏弹性人工边界模拟波从有限域向无限域传播,忽略轮轨接触及轨道不平顺的影响,通过对比分析的方法,总结地震荷载和列车移动荷载共同作用下路基在不同列车速度及轴重条件下的应力、位移和加速度的振动特征。研究结果表明:地震荷载对路基的位移振幅起主导作用,列车移动荷载对路基的应力和加速度起主导作用;路基各结构层的位移随列车轴重的增加而减小,随车速增加表现为先减小后增大;路基各结构层加速度随着列车轴重的增加而增加,随车速增加表现为先减小后增大又减小的趋势;推测车速70 m/s为列车影响的临界速度。

In order to investigate the vibration response nature of elastic homogeneous subgrade caused by the train moving load when earthquake occurs,this paper presents,a three-dimensional numerical calculation model of track structure-subgrade-foundation established by using ABAQUS software in combination with ORTRAN.By programming DLOAD subroutine,the moving load of the train was simulated.By inputting seismic acceleration at the low level of the model,the seismic load was simulated.By using 3-D viscoelastic artificial boundary,the wave propagation from finite domain to infinite domain was simulated.By ignoring the influence of wheel-rail contact and track irregularity and by using the comparative analysis method,the vibration characteristics of stress,displacement and acceleration of subgrade under the combined action of earthquake load and train moving load with different train speeds and axle loads were summarized.The results show that the seismic load plays a leading role in subgrade displacement amplitude while the train moving load plays a leading role in subgrade stress and acceleration.The displacement of each structural layer of subgrade decreases with the increase of train axle load,but decreases initially and then increases with the increase of speed.The acceleration of each structural layer of subgrade increases with the increase of train axle load,but with the increase of train speed,it shows a trend of decreasing initially,then increasing and finally decreasing.It is estimated that the speed of 70m/s is the critical speed influenced by the train.