阻尼对地铁引起地面振动计算的影响

地铁振动的频率多为中高频,且分布范围广,土体特性更是异常复杂。因此,地铁引起土体振动时,将产生复杂的拍现象,根据地铁引起土体振动频率的特性,提出确定阻尼比控制频率的合理个数和大小,从而使振动在其整个频率分布范围内的阻尼比与事先确定的控制阻尼比之差满足要求,进而建立Caughey阻尼模型;利用Caughey阻尼模型,通过有限元方法计算地铁引起土体的振动响应,并与按Rayleigh阻尼模型的计算结果进行比较,从而考察阻尼对地铁引起地面振动计算结果的影响。

Influence of damping on the caculation of subway-induced ground vibration

The frequency range of the ground vibration induced by subway trains is generally wide,and the property of soil is always complicated.Therefore,complex beat phenomena occur in the soil subjected to the subway vibration excitation with a wide range of frequencies.For the damping ratio remains close to the desired value throughout the frequency range,the number and value of the model frequencies determining the desired damping ratio are presented.Furthermore,the Caughey damping matrix is constructed.With the Caughey damping matrix,the dynamic response analysis of the soil under the action of subway-induced vibrations is made based on the dynamic finite element method.The comparison of the ground vibration responses calculated by the Caughey damping method and the Rayleigh damping method is made,and the influence of damping is presented.