The Influence of Cross-Section Shape on Failure of Rock Surrounding the Main Tunnel in a Water-Sealed Cavern

The influence of cross-section shape on rock stability was investigated by designing a similar model test and numerical simulation using particle flow code (PFC). results showed that the left- right-hand sides entrance are subjected to tension, mainly forming vertical cracks or oblique with large dip angle. vicinity is shear effect overall failure brittle in test. Mesoscopic fractures appear as tensile fractures, small number found entrance. A long narrow coalescent-fracture zone separately formed at when approaching peak load PFC Stress concentration occurs end axis elliptic cross-section. stress high arch foot spandrel horseshoe-shaped coalescent fracture side caused tunnel fail. ovoid-shaped vertical-wall-arched cross-sections under significant owing force chains distributed along wall, show included angle wall. From perspective bearing capacity, circle best section. mode, section more suitable for use corresponding practical engineering.