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采用空心圆柱仪对重塑空心软黏土试样开展了一系列非破坏试验,研究了列车循环动荷载作用下的性状。试验中主要选取心形应力路径,以圆形应力路径为辅助,对比分析了两种应力路径下软土的非共轴应变特征,探究循环振次对非共轴特性的影响、荷载频率的大小对非共轴角与大主应力方向角关系曲线形态变化的影响,同时进行了机制分析,并与另一动应力水平下试验结果进行了对比论证。此外,在不考虑频率影响下建立了简化的非共轴角与大主应力方向角之间的关系模型。研究发现,在大主应力方向角旋转的任意周期内,心形与圆形两种应力路径下非共轴角随大主应力方向角变化趋势各自有明显特点,相同动应力水平下两种应力路径产生的偏应力增量引起的单位偏应变增量大小也有所区别,但在大主应力方向角旋转的局部角度内,两种应力路径下的偏应变增量相近;心形应力路径下的非共轴角以及偏应力增量引发的单位偏应变增量大小受循环振次的影响不明显,任意振次中大主应力方向角在[-30°,40°]弧度区间内对应的偏应变增量远大于该区间之外的偏应变增量;随着频率增大,非共轴角随大主应力方向角的变化呈现越来越明显的波动。
A series of non-destructive tests were carried out on the hollow plastic samples of hollow soft clay by using a hollow cylinder to study the traits of the train under cyclic cyclic loading. In the experiment, the heart-shaped stress path is mainly selected and the circular stress path is used as an aid. The non-coaxial strain characteristics of the soft soil under two stress paths are compared and analyzed. The influence of the cyclic vibration on the non-coaxiality is investigated. The load frequency The influence of the non-coaxial angle on the shape change of the curve of the principal principal stress is analyzed, and the mechanism analysis is carried out at the same time. The results are contrasted with the experimental results under another dynamic stress level. In addition, a simplified model of the relationship between the non-coaxial angle and the principal principal stress direction angle is established irrespective of the frequency. It is found that the non-coaxial angle under the two stress paths of the major and the main stress directions have their own distinct characteristics with the change trend of the principal stress direction angle in any period of rotation of the main stress direction angle. Under the same dynamic stress level, The magnitude of the increment of unit strain caused by the increment of deviatoric stress caused by the path is also different, but within the local angle of rotation of the principal stress direction, the deviatoric deviations in both stress paths are similar; in the heart-shaped stress path The non-coaxial angle and the increase of deviatoric stress caused by the increment of unit strain are not significantly affected by the cyclic vibration. The corresponding principal deviation of the principal stress in any vibration order is in the [-30 °, 40 °] The strain increment is much larger than the increment of the partial strain outside this interval. As the frequency increases, the non-coaxial angle shows more and more obvious fluctuation with the change of the principal stress direction angle.