Abstract: The fault structure is the key factor constraining the design and construction of underground works. A unified model of the strata, faults, and underground caverns were established within a method of 3D geological modeling considering the coupling relationship of complex geological structures and underground cavern group. A concept of fault staggered and topological complexity is put forward based on the unified 3D model. And a new analysis method is provided to solve the location problem of underground caverns in the design of the hydropower engineering. In light of surrounding rock stability, an identification method of curved surface blocks based on the staggered cut of faults and the excavation faces is proposed to search the instability regions in the underground cavern group. This method has successfully applied to a hydropower engineering with underground cavern group and played an important role in program optimization and rock stability analysis.

Key words: underground caverns, faults network, complexity, 3D modeling, curved surface blocks