初始静剪应力对粗粒土与结构接触面循环力学特性的影响

Influence of initial static shear stress on cycle mechanical behavior of interface between structure and gravelly soil

运用80 t大型三维接触面试验机,对初始静剪应力存在时粗粒土与结构接触面循环力学特性及初始静剪应力大小的影响进行了研究。循环剪切时,接触面沿初始静剪应力方向产生了明显的切向位移,且该位移与正交切向的剪切路程基本呈直线关系,该直线与初始静剪应力的夹角和初始静剪应力水平关系可用二次多项式描述。初始静剪应力大小对接触面抗剪强度、正交切向应力-应变关系形式影响较小,主要影响正交切向应力峰值、接触面剪切体变数值及剪切体变与切向位移关系等。初始静剪应力越大,该方向产生的切向位移越大,其正交切向应力峰值越小,该应力峰值对应的切向位移亦越小,接触面剪切硬化程度越高;初始剪切时接触面剪胀量越大,而后期循环剪切时剪缩量和剪胀量则越小。

Applied with a new professional apparatus, the 3D cycle mechanical behavior of a gravel-structure interface is investigated considering initial static shear stress. The tangential displacement in the direction of initial static shear stress is obviously observed due to the cyclic shear application; it has a linear relationship with its perpendicular shear distance. The angle between the line and the initial static shear stress behaves in quadratic polynomial manner with initial static shear stress level. The magnitude of initial static shear stress has little influence on the shear strength and the relation pattern between tangential shear stress and strain, but has significant effect on the peak perpendicular shear stress, volumetric change and the relationship between volumetric change and tangential displacement of the interface. As the initial static shear stress increases, the peak perpendicular shear stress and the corresponding tangential displacement of the interface decrease, the interface becomes more hardened due to cyclic shear application, and dilates more at the beginning of shear application while less during subsequent cyclic shearing.