主应力轴旋转下高偏压固结粉土动力特性

为研究不同固结方式对粉土在波浪荷载引起主应力轴循环旋转下的性状影响，对长江入海口相对密实度为70%的饱和粉土进行试验。采用空心圆柱仪对重塑粉土试样，进行了固结比为1和2条件下，恒定剪应力幅值的主应力轴循环旋转动力加载，并对相关孔压、应变等数据进行数值拟合分析。结果表明，主应力轴旋转下，固结比为1的试样，随动剪应力增大，孔压开展由三阶段两相态点模式转化为二阶段单相态点模式，而主应变差则在0.2%~0.5%这一小应变范围内发生崩塌；固结比为2的试样，孔压开展仅有二阶段单相态点模式，且孔压比至0.45保持稳定，主应变差则能平稳开展至较大幅值，比等向固结试样有更高动强度。最后采用修正Seed模型及双曲线模型分别对等压及偏压固结试样的孔压开展进行了预测。研究结果较好地揭示了不同固结比粉土在主应力轴旋转下的宏观性状差异。

Dynamic behaviors of anisotropically consolidated silt under principal stress rotation

To assess the influence of consolidation ratio (Kc) on silt's behaviors under cyclic principal stress rotation (CPSR)，experiments were conducted on silt with the relative density of 70%. The remoulded silt samples with Kc=1 and 2 were tested with hollow cylinder apparatus. They underwent the CPSR stress paths with constant shear stress. And the characteristics of the pore pressure and strain were also analyzed with numerical method. The results show that under CPSR as for the samples with Kc=1,before failure the development of the pore pressure changes from three stage mode into two stage mode with the increase of shear stress. As to the strain, the maximum deviator strain is limited within 0.2％ to 0.5％ at the collapse points. While Kc=2, the pore pressure belongs to two stage mode and its ratio remains stable at the value of around 0.45. As a result, the strain can generate smoothly to large extent and the samples have higher dynamic strength than the ones with Kc=1. Eventually, the development of the pore pressure of the samples with Kc=1 and 2 were respectively predicted by the modified Seed model and hyperbolic model. The research reveals the different macro behaviors of silt under CPSR with different Kc effectively.