中文摘要：

依据非均匀锈胀理论提出钢筋锈胀作用的计算方法,应用扩展有限元法（XFEM）建立了钢筋锈胀保护层开裂的有限元模型。数值分析表明：采用XFEM与混凝土黏聚力模型能有效模拟混凝土开裂及裂纹扩展,避免了网格重剖分的问题;预裂纹的存在抑制了混凝土裂纹萌生,却加速了裂纹扩展贯通保护层,且萌生始于预裂纹尖端,而非钢筋-混凝土锈蚀层界面处;初始无损伤结构裂纹萌生位置对称分布于锈蚀层界面一定范围内,裂尖距交界面距离越大,单元受锈胀影响越小,最终贯通保护层主要是锈胀位移与锈蚀产物渗入裂缝产生作用力共同作用的结果,且裂纹扩展角趋于120°;提高混凝土等级和增大保护层厚度能有效延缓锈胀裂缝的产生与发展,有利于提高结构耐久性。

英文摘要：

Based on the theory of non-uniform corrosion expansion, a method for calculating the effect of reinforcement rust expansion was given. Also, a finite element model for simulating cracking propagation of the protection layer on the base of extended finite element method（XFEM） was established. The simu- lation analysis shows that implementation of XFEM and cohesive crack model for the analysis of concrete fracture and propagation are effective, and capable of simulating crack initiation and extension path with- out remeshing. Existence of pre-crack restrains crack initiation, which begins in the pre-crack tips instead of the interface of reinforcement and concrete, accelerates crack propagation through the cover. Never- theless, the positions of crack initiation are distributed in the interface symmetrically within a certain dis- tance for the non-defective structures. The greater of distance between crack tips and interface is, the weaker of damage of concrete element around the crack-tips. Furthermore, the rust expansion and forces produced by the infiltration into crack of the corrosion products coefficiently lead to the breakthrough of cover. In addition, the crack propagation angle tends to 120 degrees. It is effective to delay crack initia- tion and propagation by improving concrete grade and cover thickness, which can improve the durability of structures.