砂浆锚杆锚固段锈蚀胀裂过程的数值模拟及分析

NUMERICAL SIMULATION AND ANALYSIS OF COVER SPLITTING DUE TO CORROSION IN ANCHORAGE ZONE OF BOLTS

为研究砂浆锚杆锚固段的锈蚀胀裂过程,将杆体表面锈蚀产物的体积膨胀作用转化为虚拟径向位移直接作用在杆体孔洞周围,提出杆体发生均匀锈蚀和不均匀锈蚀时,根据锈蚀量确定虚拟锈胀位移的方法。用有限元软件ANSYS8.0中基于弥散固定裂缝模型的具有开裂功能的Solid65单元对砂浆锚杆锚固段保护层的锈蚀胀裂过程进行数值模拟。应用算例说明,在锈蚀量相等的情况下,杆体发生均匀锈蚀和不均匀锈蚀时,砂浆保护层的开裂程度是明显不同的,锈蚀对砂浆保护层的破坏程度是不一样的,由此提出在进行锈胀预测时均匀锈蚀假定应慎用的观点。

To investigate the process of cover splitting due to corrosion in the anchorage zone of bolts, the dummy radial displacements loaded on the hole in wall of bolts are used to simulate the expansion of corrosion products overlaying above bolts. The dummy displacements can be determined according to the quantity of iron corroded when uniform or nonuniform corrosion occurs to bolts. Then the splitting of the mortar cover due to the corrosion in the anchorage zone of bolts is numerically simulated by use of element Solid65 with the function of cracking based on the smeared fixed crack model in the finite element software ANSYS8.0. By use of an example, it is proved that when the corrosion quantity are equal, the cracks in the mortar cover and the destructive effects are obviously different around bolts uniformly and nonuniformly corroded, so the assumption of uniform corrosion should be adopted with caution in the prediction of time-to-corrosion cracking.