Mengdigou Hydropower Station is the fifth cascade hydropower station in Yalong River’s middle reaches. Due to the maximum dam height of 200 m and complex geological conditions

it is of significant importance for engineering safety to ensure the dam’s good workability and global stability after impounding. Based on deformation reinforcement theory (DRT)

a 3D finite element model of Mengdigou is built to analyze the behavior of the dam’s displacements

plastic zones extension and global stability under both normal and overloading conditions. The results show that the displacements and overloading capacity meet the stability requirement. The introduction of fillet significantly reduces the plastic complementary energy of both the dam and base

which is beneficial to the global stability. Two ways of replacement treatment for f4 fault are investigated. It turns out to be more favorable using shallow replacement together with grid replacement for the dam’s global stability.