列车荷载下海相沉积软土循环累积变形研究

Cyclic Accumulative Deformation of Marine Deposit Soft Clay under Train Loading

以宁波轨道交通1号线②、③和④层海相沉积软土为对象,进行GDS单向振动三轴试验,研究了不同动应力幅值和频率作用下软土的动力学特性.结果表明:动力幅值越大,循环累积塑性变形越大,动应力的幅值大小对累积塑性变形有较明显的影响;在动应力为12kPa时,④层粘土的累积塑性应变比相同条件下②层和③层土的应变大;在相同动应力幅值时,②和④层土随频率增大,③层土则相反.最后,利用修正的指数模型对循环加载累积塑性应变的变化进行拟合,并得到了优化的模型参数.

In this paper, the GDS single vibrations triaxial test is carried out on the marine deposit soft clay in line 1 of Ningbo urban rail transit, and the dynamic property of the soft clay in the condition of different dynamic stress amplitude and frequency is analyzed. It is shown that the greater the amplitude of dynamic stress is, the greater cyclic accumulative deformation. The uneven of the line has a great effect on the deformation. When the dynamic stress is 12kPa, the value of strain in layer ④ is greater than that in layer ② and ③ in the same condition. The strength of layer ② and ④ increases with increasing frequency under the same dynamic stress and on the contrary the law occurs in layer ③. At last, a modified exponential model is constructed to describe the change of the cyclic accumulative strain, and the optimizational parameters for the model are obtained.