The principle of 3D elasto-viscoplastic block element method is introduced. This method exclusively takes deformation and strength property of the discontinuities into consideration

with the assumption that the rock blocks are rigid. The governing equation is deduced on the base of the equilibrium equation of block system

the compatible equation of displacement between the discontinuities and blocks and the elasto-viscoplastic constitutive equation of discontinuities. In right abutment slope of Longtan Hydropower Station

the geology is complicated

and the stability of blocks is a serious question. The 3D elasto-viscoplastic block element method is adopted to analyse the stability of the given blocks limited by the typical discontinuities

a series of safety factors of strength reservation under various work conditions are obtained. In the same time

the sensitivity analysis is performed aimed at such important factors influencing the stability of blocks as geometrical and mechanical parameters of discontinuities to provide proposals for engineering design. The application indicates that

as a new numerical method for hydraulic engineering

the elasto-viscoplastic block element method has the merits of validity

practicability and convenience for the stability and deformation analysis of block slope with complicated geology.