Excavation Method Analysis of Neighborhood Tunnel on Expressway

Abstract

Neighborhood tunnel is a special structural type with a clear distance between multi-arch tunnel and usual separated tunnel’s minimum required in the tunnel design regulations. The clear distance is small, so the interaction of two tunnels is relatively great, which will greatly influence the stability of surrounding rock especially interlaid rock. Therefore, it is very necessary to seek a safe, convenient and economical excavation method for neighborhood tunnel. Combining with an expressway neighborhood tunnel engineering practice (with clear distance 4.0m, buried depth 30.0m) withⅡ-class surrounding rock and by three-dimension elastic-plastic element numerical simulation, this paper analyzed the surrounding rock destruction approaching degree and deformation characteristics separately according to cheek pilot method, combination method, and up-down bench method of double tunnel. On the basis of the analysis, this text studies advantages, disadvantages and adaptability of each of the three different excavation methods, to provide scientific reference for design and construction of freeway neighborhood tunnel.