Analysis on surrounding rock masses� stabilities for underground cavern group

Abstract

Abstract. Surrounding rock masses' stabilities of cavities and crane beams of the hydropower station were studied using FLAC 3D . Results show that, due to the large excavation span and height, the main powerhouse and tail water hole have larger plastic zones after the excavation, and the same as 1 # unit and 2 # unit affected by the alteration belt; after the excavation, the plastic zones of the main powerhouse and main transformer hole appear connected and it is reduced obviously after support; from the comprehensive consideration of cavities' stabilities and economic benefits, scheme 3 ( bolts and nineteen cables ) is the optimal supporting plan, apt to ensure the overall stability of surrounding rock; displacements of surrounding rock and bolts' axial forces of crane beams are caused mainly by excavation, while the parts caused by wheel pressure are small. This offers a reliable basis for stability analysis and supporting design for underground cavern group.