不同初始状态软黏土在主应力轴耦合旋转下的孔压及3维变形规律

土体在受波浪、地震以及交通荷载等荷载作用时，其相应的应力状态较为复杂，以致于偏应力和主应力轴方位角同时变化的情况普遍存在于实际工程中，目前关于这种应力条件下原状软黏土的物理力学特性的研究尚处于起步阶段。主应力轴耦合旋转即是指在主应力轴方向旋转的同时，偏应力不断增大，而平均主应力、中主应力系数均保持不变。本文为了研究主应力轴耦合旋转时原状软黏土的变形和孔压特性，基于空心圆柱扭剪系统（HCA）对原状软黏土进行了一系列不同初始状态的扭剪试验，探讨了不同固结倾角、中主应力系数在主应力轴耦合旋转条件下对原状软黏土的变形、孔压等特性的影响。结果表明：不同初始固结状态对软黏土的变形特性有明显的影响；主应力轴耦合旋转过程中软黏土试样在b = 0和b = 0.5时的轴向变形以受压为主，在 b = 1时试样的轴向变形在主要表现为受拉状态；不同固结倾角下，主应力轴耦合旋转下试样的轴向、环向和剪切变形趋势均有明显的不同，径向应变值差别不大，在b = 0.5时试样的径向应变值接近0；不同初始固结倾角条件下试样的孔压峰值对应的大主应力方位角也不同，孔压累积与应变开展并不一一对应；应力和应变的变化与偏应力和主应力方位角的增加不同步，即存在明显的非共轴现象。

Generation of Pore Pressure and Three-dimensional Deformation Behavior of Soft Clay with Different Initial State Under Combined Principal Stress Rotation

As subjected to complex loads, such as wave, earthquake and traffic loads, the corresponding stress state of the foundation soil will become more complicated. The simultaneous variation of deviator stress and the principal stress direction occur in practical engineering. However, there are few studies on properties of natural soft clay under combined principal stress rotation, combined principal stress rotation means that deviator stress and major principal stress direction are simultaneously increasing during shearing, with the mean principal stress and the intermediate principal stress coefficient remain unchanged. In order to study the deformation characteristics of saturated natural soft clay under combined principal stress rotation, the torsional shear test of natural soft clay was carried out based on hollow cylinder apparatus (HCA) in this paper. The influence of different inclined consolidation and intermediate principal stress on the deformation and pore pressure of natural soft clay under combined principal stress rotation are discussed. It can be obtained that the deformation behavior and pore water pressure accumulation of tested samples are significantly influenced by intermediate principal stress coefficient b; The compressive deformation is dominated in the axial direction under b = 0 and b = 0.5, and extensive deformation is dominated under b = 1; The generation of axial, circumferential and torsional deformation is different obviously, while the radial deformation is almost the same, the value of radial stain is approximate 0 when b = 0.5. The corresponding major principal stress angles to the maximum value of pore water pressure are different under different inclined consolidation conditions. The variation of stress and strain components is not synchronous with the increase of deviator stress and principal stress direction, means that the non-coaxial behavior existed