Damage identification of arch dams based on post-earthquake residual displacement gradients

Current research on the identification of damage to arch dams under strong earthquakes is few, and the limited damage identification methods are primarily based on seismic acceleration records. For statically indeterminate arch dams, these methods can only represent the overall equivalent damage, but the identification accuracy of dam damage, particularly local damage, is not very good. Using the displacement monitoring system installed at the dam, the post-earthquake residual displacement (RD) of the arch dam may be obtained; however, the cor-relation between the RD at the dam crest and the dam damage is poor and does not permit a quantitative assessment of the dam damage. Therefore, a damage identification method based on post-earthquake RD gra-dients is proposed in this paper. First, the RD distribution and damage distribution features of Baihetan arch dam (289 m) under strong earthquakes are examined. Then, the relationship between the RD and the position and magnitude of the damage in the mid-upper region along the arch crown cantilever (ACC) of the arch dam was determined. Finally, parametric analysis was used to investigate the effects of the measuring point layout scheme on the reconstructed RD information along the ACC. The results indicate that the dam damage identification method based on RD gradients is accurate, and the proposed simplified measuring point layout scheme can capture RD gradient information along the ACC with high precision.