(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. Anhui Communications Planning，Design and Research Institute，Hefei，Anhui 230041，China)
Abstract：Based on the analyses of stability control factors of shallow-buried tunnel adjacent to mountain and the disadvantage of traditional design scheme，a new type of tunnel structure，permeable tunnel with ribbed arch beam，is presented. Combining pre-reinforcement of the vault slope with cross-mounted pipe-shed and ribbed arch beam structure，a reasonable and complete supporting system is formed；and the excavation scope of the tunnel reduced significantly and no ventilation system and lighting system is needed. This tunnel structure comprehensively reflects the design idea of engineering safety，environmental protection，energy conservation and landscape coordination. With practical engineering，the design principle and structural characteristics of this tunnel are expounded；and the characteristics of stress and deformation and the schemes of excavation and reinforcement are analyzed by numerical simulation method. The analytical results reveal that the relaxed region of tunnel surrounding rock can be determined，and the cross-mounted pipe-shed is designed to reinforce the vault slope. By comparative analysis of different excavation schemes，the optimal construction program is suggested that is suitable for the cavern rock firstly and the integrated concrete in the ribbed arch beam and the tunnel-lining，which can lower the stress level of the tunnel structures and homogenize the stress distribution. The permeable tunnel with ribbed arch beam has been built successfully，so as to verify the reasonability of above-mentioned research results and the construction scheme of this kind of new tunnel.
