中文摘要：

基于GDS循环动三轴试验,首先对比了不同形式的动荷载作用效果,结果表明偏压正弦波模拟列车循环荷载效果较好。然后研究了初始固结度和加载频率对地铁荷载作用下软黏土动力特性的影响,结果表明：排水加载条件下原状土孔压发展趋势分为2个阶段,第1阶段孔压迅速上升,达到峰值后进入第2阶段,表现为孔压下降且降速渐缓并趋于稳定;初始固结度越大,土样的累积峰值孔压越小,孔压消散时间越短;原状土应变发展呈现稳定型,固结度越低,轴向应变越大,应变稳定所需时间越长;且低频引起的累积应变较大,工程中应予以重视。提出的孔压及应变模型可较好地模拟列车荷载作用下不同固结度的原状软黏土的动力特性规律。

英文摘要：

Based on dynamic tri-axial test of undisturbed soil,the effects of different forms of dynamic loads were compared at first.The results showed that the bias voltage sine wave showed better effect in simulating the train cyclic loading.After that,the influence of initial consolidation degree and loading frequency on the dynamic characteristics of soft clay under subway loading was studied further.The results showed that the development trends of the pore pressure of the undisturbed soil were divided into two stages under partially drained conditions.In the first stage,the pore pressure increased rapidly,reaching apeak value before entering the second stage,in which the pore pressure decreased slowly to a final stable value.A lower accumulative peak pore pressure was corresponded to a higher initial consolidation degree,with shorter pore pressure dissipation time.The strain of undisturbed soil presented a stable trend,showing the increase of the axial stain with the decline of consolidation degree,and longer time it took to be stable.A low frequency can significantly enlarge the strain value,which deserves more attention in practical engineering.The model of pore pressure and strain presented in this paper can simulate the dynamic characteristics of undisturbed soft clay with different consolidation degrees under the train load.