武广高速铁路无砟轨道路基动力响应试验研究

在武广高速铁路典型路基断面埋设测试元件，分别于“联调联试”阶段和运营2年后进行了动车组列车荷载作用下的路基动力试验，实测了路基动应力、振动加速度、振动速度等动力响应。分析了路基动力响应与列车速度的关系、动力响应沿路基深度变化规律和路基动力特性在运营前后的变化情况。结果表明：基床表层顶面轨下位置动应力响应比中线处大；动态响应在基床表层范围内最为强烈且衰减较快；列车荷载速度对动应力幅值影响较小，对振动加速度幅值影响较大。运营2年后与“联调联试”阶段相比，基床表层顶面动应力幅值、振动速度幅值相差不大，而振动加速度幅值在“联调联试”阶段较大；两次试验测得的z=2.7m时(基床底层底面)路基动应力幅值和振动加速度幅值的衰减率依次为73.40%~79.30%和79.28%~86.90%，z=4.2m时（路基本体内）两者衰减率依次为82.99%~89.06%和92.78%~96.31%；而振动速度幅值，z=1.8m时（基床底层内）衰减率范围为75.62%~80.80%。

Experimental Study on the Dynamic Response of Ballastless Track Subgrade in Wu-Guang High-Speed Railway

The dynamic responses of subgrade, containing dynamic stress, vibration acceleration and vibration velocity, have been obtained in the filed test under EMU load in the Wuhan~Xianning typical section in Wuhan-Guangzhou high-speed railway , carried out separately in the alignment league try stage and during operation after 2 years. In the paper, the relationship of train speed and the dynamic response has been analyzed; the law of dynamic respone along the roadbed depth, and the change of the dynamic respone of subgrade before and after the operation has been discussed. The results indicate that along the subgrade surface cross section, the dynamic stress response has the nonuniform distribution, the measured value under rail bigger than the median line area; the most intense dynamic respones are measured on the surface and graded gravel area; it reduces sharply with the increase of depth. The speed of train loads has a smaller impact on the dynamic stress, while a greater influence on the vibration acceleration. Comparing during operation 2 years later with in the alignment league try stage, the dynamic stress and vibration velocity of the surface layer of subgrade bed differ little, but the corresponding acceleration change greatly. Practical experiments show that the range of attenuation rate of dynamic stress and dynamic acceleration at z=2.7m is respectively 73.40%~79.30% and 79.28%~86.90% , while 82.99%~89.06% and 92.78%~96.31% at z=4.2m; the scope of attenuation rate of vibration velocity at z=2.7m is 75.62%~80.80%.