以地铁隧道内常使用的DT VI2型扣件为研究对象,采用车辆—轨道垂向耦合随机振动频域分析模型与有限元谱分析模型组合求解法,研究扣件胶垫阻尼的频变性对地铁隧道环境振动的影响。结果表明:与常量的扣件胶垫阻尼相比,随频率变化的扣件胶垫阻尼对地铁隧道环境低频振动影响很小,但会增大其分频最大振级,同时还会降低其分频最大振级以上频带内的振动水平,并且随着频率的持续提高,振动级的下降幅度也会越来越大;尽管可以通过单纯降低胶垫阻尼系数提高地铁隧道环境振动频域的预测精度,但难以保证对各频段振级均有较高的预测精度,因此,如不考虑扣件胶垫阻尼的频变性,易低估地铁隧道环境振动的分频最大振级,同时会高估主频段以上的振动水平。
Taking DT VI2 fasteners commonly used in metro tunnel as research object,the model for analyzing the frequency-domain stochastic vibration of vehicle-track vertical coupling and the model for analyzing the spectrum of finite element were combined to investigate the influence of the frequencydependent damping of rail pad on the environment vibration of subway tunnel.The results show that the frequency-dependent damping of rail pad has little effect on the low-frequency environment vibration of subway tunnel,compared with the constant damping of rail pad,but it will increase the maximum vibration level in its frequency division and at the same time decrease the vibration levels in the frequency bands above its frequency division with the maximum vibration level.Besides,the decrease range of vibration level becomes greater and greater with the continuous increase of frequency.Simply reducing the damping coefficient of rail pad can improve the prediction accuracy for the environment vibration in frequency domain of subway tunnel,but it is hard to guarantee the higher prediction accuracy for the vibration level of every frequency band.Thus,regardless of the frequency-dependent damping of rail pad,the maximum vibration level of environment vibration in frequency division of subway tunnel is liable to be underestimated,and meanwhile the vibration levels above the dominant frequency band will be overestimated.