粗粒土与结构接触面静动力学特性的大型单剪试验研究

Monotonic and cyclic behaviors of coarse-grained soil-structure interface using large-scale simple shear device

运用80 t大型三维接触面试验机,对单剪条件下粗粒土与钢板接触面静动力学规律进行了研究。随单调剪切的进行,接触面土体变形由靠近结构面区域逐渐向远处传递和发展,并集中于剪切区域内,接触面厚度约为（6~7）D50;接触面达到强度时对应的滑动位移约为0.5D50,之后滑动位移发展变快,破坏发生在接触界面处;法向应力对接触面厚度、土体变形沿试样深度分布形式影响较小,主要影响土体变形大小。循环剪切时接触面厚度未继续扩展;土体变形及变形位移幅值随循环剪切逐渐减小,并向初始剪切方向偏移,出现了异向性;接触面在不断剪切硬化,主要由结构面附近土体硬化所致;接触面强度是否达到主要取决于滑动位移,并在达到后逐渐减小,减小程度达16%,且正反向剪切时强度呈现异向性;接触面剪切体变、切向应力与3种位移（切向位移、变形位移、滑动位移）的关系稍有差别。

By using a professional simple shear device, the monotonic and cyclic behaviors of coarse-grained soil-steel interface are investigated. The soil deformation occurs firstly near the structural plate and then transfers far away due to monotonic shear application. The soil deformation is restrained to a localized shear zone, whose thickness is approximately 6D50-7D50 （mean size）. The sliding displacement occurs at the starting of shearing and increases faster after the shear strength is mobilized at the sliding displacement of about 0.5D50, indicating that the interface fails at the contact surface. The normal stress has a significant effect on the magnitude of soil deformation, but has little influence on its profile and the interface thickness. As for the cyclic shearing, the interface thickness remains invariable. The soil deformation presents anisotropic response since it migrates to the initial shear direction; and its amplitude decreases with shear cycles, revealing that the soil as well as the interface becomes hardened due to cyclic shear application. The mobilization of the interface shear strength mainly depends on the magnitude of sliding displacement, and after mobilized, the shear strength reduces by 16% with shear cycles and is also anisotropic.