摘   要：为了研究早龄期普通混凝土直剪作用下的力学性能，完成了12个普通混凝土试件的直剪试验，获取了试件的破坏形态及直剪荷载-位移全过程曲线，分析了直剪作用下龄期对普通混凝土直剪强度、峰值变形、变形模量、损伤演变、能量耗散等力学特征参数的影响规律。结果表明：龄期越长，受剪荷载-变形曲线上升段越陡峭；当龄期≤3 d时，混凝土断面剪切破坏形态为骨料与水泥基体之间界面的黏结破坏，当龄期≥7 d时，剪切破坏形态为骨料与水泥基体之间界面的黏结破坏与粗骨料本身的剪断破坏；随着龄期的延长，普通混凝土试件的峰值剪切变形减小，直剪强度、变形模量和能量耗散系数增大，混凝土损伤的出现变晚。

Abstract: In order to study the mechanical properties of ordinary concrete at early age under direct shear, a total of 12 test blocks were designed and completed for the direct shear. The failure patterns and direct shear load-displacement process curves of the specimens were obtained, and the influence rules of mechanical properties such as shear strength, peak deformation, deformation modulus, damage evolution and energy dissipation of ordinary concrete were analyzed at different ages under direct shear. The results show that the longer the age, the steeper the rising section of the shear load-deformation curve. When the age is less than or equal to 3 d, the shear failure of the concrete section is the bond failure between the aggregate and the cement matrix. When the age is greater than 7 d, the shear failure form is the bond failure of the interface between the aggregate and the cement matrix and the shear failure of the coarse aggregate. As the age increases, the peak shear deformation of the ordinary concrete specimen decreases, the shear strength, deformation modulus and energy dissipation coefficient increase, and the appearance of concrete damage becomes later.