装配式结构套筒灌浆连接的混凝土结合界面直剪性能试验研究

研究灌浆层厚度、纵向钢筋、配筋率、轴向压力等因素对直剪荷载作用下套筒灌浆连接的混凝土结合界面裂缝开展、破坏形态、直剪剪切强度、裂缝-滑移曲线以及荷载-滑移曲线的影响. 试验结果表明：对于无纵向钢筋试件结合界面，灌浆层厚度为1、10 mm界面的破坏荷载均值分别是灌浆层厚度为20 mm界面的1.69、1.14倍；对于纵向配筋结合界面，配筋率为0.9%、1.8%的试件界面破坏荷载均值分别是无筋试件界面的1.58、1.89倍，且结合界面直剪破坏延性显著提高，但由于未配箍筋，最终破坏形态为混凝土被纵向钢筋劈裂破坏，降低了结合界面的直剪剪切强度和延性；对于施加轴向压力试件，轴向压力为11.6、23.2 MPa的试件界面破坏荷载分别为无轴压试件界面的6.06、7.81倍，在23.2 MPa轴向压力下，破坏模式转化为界面破坏后的现浇部分混凝土本体破坏.

Experimental study on direct shear performance of concrete-concrete interface of prefabricated structure sleeve grouting connection

The effects of grouting layer thickness, longitudinal reinforcement, reinforcement ratio and axial pressure on cracking development, failure pattern, direct shear strength, crack-slip curve and load-slip curve of concrete-concrete interface under direct shear loading were studied. The test results show that, for the interface without longitudinal reinforcement, the average failure loads of the specimens on the grouting layer with thickness of 1 and 10 mm were 1.69 and 1.14 times of that with the thickness of 20 mm, respectively. For the concrete-concrete interface with longitudinal steel bars, the average failure loads of the specimens with the reinforcement ratio of 0.9% and 1.8% were 1.58 and 1.89 times of that of the unreinforced specimens, respectively. In addition, the ductility of interfacial direct shear failure is significantly improved. However, for the reinforced specimens without stirrups, the failure pattern developed into concrete splitting failure by longitudinal steel bars, which can reduce the direct shear strength and ductility of the concrete-concrete interface. For the concrete-concrete interface under axial pressure, the average failure loads of the specimens under axial compressive stress of 11.6 and 23.2 MPa were 6.06 and 7.81 times of that of the unpressurized specimens, respectively. Under axial pressure of 23.2 MPa, the failure mode is transformed into the failure of cast-in-place concrete after the interface failure.