Stability analysis of the permanent shiplock slopes of the three gorges project

The stability of the permanent shiplock slopes is among the key issues in the design and construction of the Three Gorges Project in China. The unloading process due to excavation has negative effects on the mechanical properties of the rock mass in the slopes. This paper employs both the upper bound limit analysis and a finite element method (2D and 3D) to evaluate the stability of permanent slopes under the effects of excavation. The results from different methods effectively support and complement each other. The calculated factors of safety confirm the adequacy of the geological condition for ensuring overall stability of the slopes. After the excavation, the tensile stress and shear-damaged zones mainly occur at the middle and upper parts of central rock barrier and vertical walls. The dominant sliding path would not be formed by the extension and linkage of the local potential sliding surfaces. The global stability of the permanent slopes can be assured. The reinforcement would be required to prevent the local collapse during construction and operation stage.