基于XFEM的混凝土保护层锈胀裂纹分析  

Analysis of corrosion-expansion-induced cracks on concrete cover based on XFEM

作　　者：汪奔 王弘[1] 张志强[2] 周蒙蛟[1] 

机构地区：[1]西南交通大学力学与工程学院应用力学与结构安全四川省重点实验室,四川成都610031 [2]西南交通大学土木工程学院,四川成都610031

出　　处：《河海大学学报（自然科学版）》2017年第2期161-166,共6页Journal of Hohai University(Natural Sciences)

基　　金：国家自然科学基金(51478396;51078318);四川省青年科技创新团队基金(2013TD0004)

摘　　要：采用扩展有限元法(XFEM)和过盈装配的方式,建立了混凝土保护层非均匀锈胀开裂有限元模型。计算结果表明:首先在与钢筋接触的左右两侧10°~30°范围内形成包含数条微裂纹的裂纹带,对称于钢筋的中轴线背向发展,随着锈蚀程度的加深,在裂纹带形成一条斜向的主裂纹,从而导致保护层产生"楔形"破坏。通过对ABAQUS进行二次开发,提取了锈胀裂纹长度,发现裂纹长度与钢筋锈蚀率之间呈指数关系,指出裂纹发展可分为3个阶段(萌生区、扩展区和平缓区),应以裂纹进入平缓区的钢筋锈蚀率对结构进行评估,并给出了界限判据。与广惠高速公路沿线桥梁保护层剥落病害对比分析,验证了计算结果的精确性。A finite element model of non-uniform corrosion-expansion-induced cracking of a concrete cover was built using the extended finite element method （XFEM） and interference fit assembly. The calculated results show that a cracking band including several microcracks occurred across a range of 10° to 30°, adjacent to steel bars on their left and right sides, and developed symmetrically in the backward direction away from the medial axis of the steel bars. With increasing degree of corrosion, a diagonal main crack occurred in the crack band, resulting in wedge- shaped destruction of the concrete cover. By means of the secondary development of ABAQUS, the length of corrosion-expansion-induced cracks was obtained, and an exponential relationship between the crack length and the corrosion ratio of steel bars was deduced. The cracking development can be divided into three stages, corresponding to the occurrence of the embryonic zone, extending zone, and gradual development zone of cracks, and the corrosion ratio of steel bars, when cracks enter the gradual development zone, can be used to evaluate the durability of structures. The accuracy of the calculated results was verified by comparison with damage of bridges on Guanghui Expressway induced by concrete cover desquamation.

关 键 词：混凝土保护层 钢筋锈蚀 裂纹 XFEM 数值模拟 广惠高速公路沿线桥梁 

分 类 号：TU375[建筑科学—结构工程]