Tan Jiacheng, Shen Zhenzhong, Xu Liqun, Zhang Hongwei, He Yingming
State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China.
College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China.
Materials (Basel). 2022 May 26;15(11):3802. doi: 10.3390/ma15113802.
There exist shear and seepage behaviors on the interface between clay core and concrete slab in clay core dams. In order to investigate the seepage characteristics of the clay-structure interface after shear deformation, a shear-seepage test system is proposed, in which the seepage direction is perpendicular to the shear direction. The shear test and shear-seepage test are performed on clay-metal and clay-mortar interfaces under different normal stresses (100, 200, 400, 800, and 1600 kPa). The shear stress-deformation curves of two clay-structure interfaces exhibit softening behavior and residual friction behavior. The interface roughness can enhance peak and residual shear strength and increase peak displacement. The shear-seepage test results show that specimen permeability decreases first and then increases to a stable value as shear deformation increases under low normal stress, while it decreases continuously and then retains stability under high normal stress. The interface roughness enhances specimen permeability under low normal stress, whereas it has a weak effect on specimen permeability under high normal stress. Compared with initial permeability, shear deformation reduces specimen permeability rather than raise it. The ratio of stabilized permeability coefficient to initial value ranges from 0.6 to 0.8. The clay-structure interface still has a good resistance to seepage failure after shear deformation. The shear dilation features and interface pore decrease caused by shear behavior are the internal attributions of clay-structure specimen permeability evolution.
黏土心墙坝黏土心墙与混凝土面板之间的界面存在剪切和渗流行为。为了研究黏土与结构界面剪切变形后的渗流特性，提出了一种渗流方向垂直于剪切方向的剪切-渗流试验系统。在不同法向应力（100、200、400、800和1600 kPa）下，对黏土-金属和黏土-砂浆界面进行了剪切试验和剪切-渗流试验。两种黏土与结构界面的剪应力-变形曲线均呈现出软化特性和残余摩擦特性。界面粗糙度能够提高峰值抗剪强度和残余抗剪强度，并增大峰值位移。剪切-渗流试验结果表明，在低法向应力下，随着剪切变形的增加，试样渗透率先减小后增大至稳定值，而在高法向应力下，试样渗透率持续减小然后保持稳定。界面粗糙度在低法向应力下会增大试样渗透率，而在高法向应力下对试样渗透率的影响较弱。与初始渗透率相比，剪切变形会降低而不是提高试样渗透率。稳定渗透系数与初始值的比值在0.6到0.8之间。黏土与结构界面在剪切变形后仍具有良好的抗渗流破坏能力。剪切扩容特性以及剪切行为导致的界面孔隙减小是黏土与结构试样渗透率演化的内在原因。
