交通荷载应力路径下砂土地基变形特性研究

在交通荷载作用下,地基土单元不仅偏应力大小周期性变化而且主应力轴连续旋转。为了研究交通荷载应力路径下地基土单元排水变形特性,利用动态空心圆柱仪对K0固结下饱和砂土进行了一系列"苹果型"动力循环应力路径以及普通动力循环应力路径试验。两组应力路径试验结果的对比表明交通荷载应力路径引起的主应力轴连续旋转会加速竖向永久变形的累积,并且对竖向回弹模量具有软化作用,而且随着循环应力比的增大,两种应力路径下变形特性差异变得更加明显。最后,基于Uzan回弹模量模型提出了相应的修正公式用来考虑主应力轴旋转效应。

Deformation behaviors of sandy subgrade soil under traffic load-induced stress path

Under traffic load, the magnitude of deviatoric stress of subgrade soil varies periodically, and the principal stress axis rotates continually. In order to study the drained deformation behaviors characteristics of subgrade soil due to traffic load-induced stress path, a series of apple-shaped dynamic cyclic stress path tests and conventional dynamic stress path tests are conducted on K₀-consolidated saturated sand using the dynamic hollow cylinder apparatus. Comparisons between the results under the two different stress paths indicate that the continuous rotation of the principal stress axis will accelerate the accumulation of the vertical permanent strains and aggravate the degradation of the resilient modulus. And with the increasing of CSR, the discrepancies in the deformation behaviors under different stress paths become more apparent. Finally, a modified formula for the resilient modulus is proposed to evaluate the principal stress rotation effects based on the Uzan model.