新老混凝土界面直剪力学性能测试研究

Experimental Research on Mechanical Properties of New-to-old Concrete Interface Under Direct Shear Condition

新老混凝土界面不同承载方式的抗剪性能是加固结构中的关键,因此,开展了新老混凝土界面倾角和法向应力对剪切性能影响的试验测试,分析了剪切破坏特征,研究结果表明:新老混凝土剪切过程中剪应力-剪切位移曲线大致经历线弹性变化阶段、破坏阶段和残余强度阶段;新老混凝土峰值剪应力随着界面倾角增大呈幂指数增大,随着法向应力增大呈线性增大;新老混凝土剪切破坏一般表现为剪胀-剪缩混合型;界面倾角和法向应力对剪切破坏裂纹扩展模式裂纹分布影响显著。

The shear performance of new-to-old concrete interface with different loading modes is the key to the reinforcement structure.Therefore,the experimental tests of dip angle and normal stress of new-to-old concrete interface on shear performance were carried out,and the shear failure characteristics were analyzed.The results showed that the curves of shear stress and shear displacement about new-to-old concrete were roughly divided into the linear elastic change stage,the failure stage,and the residual strength stage.The peak shear stress of new-to-old concrete increased exponentially with the increase of interface dip angle and linearly with the increase of normal stress.During the shear process of the specimen,the shear failure of new-to-old concrete was generally characterized by dilatancy and shrinkage.The dip angle and normal stress of interface had significant effects on the crack propagation mode and the crack distribution.