主应力轴循环旋转下饱和软黏土的累积变形

Cumulative deformation of saturated soft clay subjected to cyclic rotation of principal stress axis

交通荷载下地基中土单元的主应力大小和方向将同时发生变化,现有的计算交通荷载引起的路基长期沉降实用模型未能反映交通荷载引起的土体单元主应力轴循环旋转现象。在推导常广义剪应力主应力轴循环旋转方程及验证空心圆柱剪切仪动力加载能力基础上,对上海第④层饱和软黏土进行一系列常广义剪应力主应力轴循环旋转加载试验及非等向固结下循环扭剪试验,分析了主应力轴旋转角、围压及静偏应力对循环塑性累积广义剪应变的影响。将常广义剪应力主应力轴循环旋转加载试验等效成不同不排水静偏应力和动应力循环旋转加载试验,从而进一步验证了文献[12]所提出的显式模型在模拟主应力循环旋转效应方面的可靠性。

The magnitude and direction of the principal stress of roadbed soil element will chang simultaneously under traffic loading. The traditional model based on tri-axial cyclic loading test data can not reflect the phenomenon of the principal stress rotation. After the axial stress-controlled equation and the circumferential shear stress-controlled equation are derived, a series of consolidated undrained cyclic shear tests are performed under the condition that the value of the general shear stress is constant and the principal stress angle is rotating. At the same time the cyclic torsional shear tests are performed under the condition of K0 consolidation. The element affecting the plastic accumulative strain is analyzed. The test that the value of the general shear stress is constant and the angle of the principal stress is rotating is equivalent to those that the static deviatoric stress and dynamic stress are different. The explicit strain model in the 12th reference is verified to calculate the accumulative strain caused by the cyclic loading of the principal stress axis