地铁列车作用下软黏土的动力响应试验研究

土体动力特性的研究对地铁列车荷载作用下软黏土地基变形的控制具有重要意义,通过对广州地铁饱和软黏土进行动三轴试验,研究土体的动强度、动应力-动应变关系和动模量特性。结果表明:(1)在循环荷载作用下,该软黏土的动强度低于45 kPa;稳定型和破坏型的ε_d-N曲线变化规律不一致;(2)在同一动应力幅值作用下,当动应变低于动应变极限值时,频率对动骨干曲线的影响较小;(3)其他条件相同时,在振动中期,频率对动弹性模量的影响较小;在振动后期,动弹性模量的衰减程度随频率的增大而增大;土体动弹性模量随动应力幅值的增大而增大;(4)最后通过Hardin-Drnevich模型验证本文基于实验数据得到的新的归一化的试验参数是合理的,且新模型参数可为该地区同类地铁工程的软黏土动力特性研究提供参考。

Study on Dynamic Response Test of Soft Clay under Subway Train Load

The study of soil dynamic properties is of great significance for the control of the deformation of soft soil foundation under subway train load. By conducting dynamic triaxial test on soft clay of Guangzhou Metro, the effects of high frequency and dynamic stress amplitude on the dynamic strength, dynamic stress-dynamic strain relationship and dynamic modulus of the soft clay are studied. The results show that: i) The dynamic strength of the soft clay is less than 45 kPa under the cyclic load, and the changes of the stable and destructive ε_d-N curves are inconsistent. ii) Under the same dynamic stress amplitude, the frequency has little effect on the dynamic backbone curve when the dynamic strain is less than the ultimate value. iii) When other conditions are the same, the effect of frequency on the dynamic elastic modulus is very small in the middle of vibration. While, the attenuation degree of the dynamic elastic modulus increases with the increase of frequency at the late stage, and the dynamic elastic modulus of the soft clay increases with the increase of the dynamic stress amplitude. iv) At last, the new normalized test parameters are verified reasonable and reliable by Hardin-Drnevich Model based on test data, and the results reveal that the new normalized test parameters can provide references for the study of dynamic properties of the soft clay in similar projects of the region.