交通荷载引起的主应力轴旋转室内试验模拟探讨

Discussion on laboratory test simulation of principal stress axes rotation induced by traffic loading

为了通过室内试验研究交通荷载引起的主应力轴旋转对土体循环特性的影响,以单个移动荷载和列车荷载为例,分析了主应力轴旋转特点。以此为基础,结合空心圆柱仪的加载特点,给出了室内模拟主应力轴旋转的加载方法。竖向动应力可以用具有静偏应力的正弦荷载模拟,动剪应力可以用正弦荷载模拟,两者的相位差为π/2。为了模拟交通荷载引起的主应力差变化的特点,两种动应力的幅值应该是不同的。当试验中施加无应力反向的竖向动应力时,大主应力夹角在-π/2～-π/4和π/4～π/2之间变化。

In order to study the effect of principal stress axes rotation induced by traffic loading on cyclic properties of soft clay in tests, one moving load and one train load are taken as examples to analyze the characteristics of principal stress axes rotation. On the base of loading properties of hollow cylinder apparatus, loading method to simulating the principal stress axes rotation in laboratory tests is given. The vertical dynamics stress can be simplified as sine wave with static deviator stress; and dynamic shear stress can be simplified as a sine wave. The phase difference between the two waves is π/2. In order to simulate the character of principal stress difference changing continuously induced by traffic loading, the amplitudes of vertical stress and shear stress should be different. It is found that the angle of the maximum principal stress is between -π/2 and -π/4 or between π/4 and π/2 when vertical stress without stress reversal is exerted.