Analysis on surrounding rock masses' stabilities for underground cavern group

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.