Abstract: A large rock landslide in the Three Gorges reservoir area involved several complex mechanisms relating to geological, environmental and human engineering activities processes. In response to deformation and failure specificities and trigger mechanism of the landslide, reinforcement measures involving cutting, large section anti-slipping piling, drainage system are used to insure the holistic and local stability of landslide zone. While the validity and applicability of reinforcement sequences of landslides are among the key issues in the whole treatment project. According to analysis of large deformation numerical method and characteristic of landslide treatment project, large deformation numerical methods for analyzing effect of landslide treatment project are proposed. The 3D Fast Lagrangian Analysis of Continua(FLAC) method is adopted to proceeding optimum design of reinforcement schemes, based on analyzing the change of displacement and damaged zone. Treatment effect obtained by all kinds of methods and their combination are compared with each other; and the best treatment scheme involving anti-slipping piling and cutting complementing drainage system is selected as the proposed scheme. The present investigation has provided both factual data and insights for the stability and deformation evaluation of the landslide. The approach and methodology developed are useful for the prevention and treatment of the similar landslides in the Three Gorges reservoir area.

Key words: rock mechanics, landslide, nonlinear large deformation FEM, optimum design, evaluation of effectiveness