At present

the viscoelastic method is widely used in the dynamic analysis of concrete faced rockfill dams (CFRDs)

basically forming a method framework: the viscoelastic model for calculating the dynamic response and the permanent deformation model for calculating the permanent deformation. Then the dam safety is evaluated through both the dam dynamic response and the permanent deformation. However

when the current method is used in the dynamic analysis of the CFRDs

there is an obvious defect

i.e.

it cannot consider the influence of permanent deformation on the stress of the concrete slab during the strong earthquakes

which may cause serious errors when applying the method in CFRDs with obvious permanent deformation. Therefore

it is necessary to improve the current method. This paper suggests to adopt the strategy of “divide first and combine later”. Firstly

the dynamic displacement and permanent displacement of the dam are calculated separately

then the two are added as the actual displacement of the structure

and finally

the strain and stress of the structure are calculated based on this actual displacement. This paper took the Yulong Kashi CFRD as an example to illustrate the necessity of the improvement.