Stability analysis of overlying stratum structure of shallow tunnel

摘要

By analyzing lots of observational materials and research results, the concept of 'zoning of and layering overlying stratum structure of shallow tunnels' is proposed,and it is concluded that there exists 'three zones five layers' in overlying stratum of shallow tunnel, which are advancing deformation zone (ADZ), loosen deformation zone (LDZ) which is the substantial zone and should be researched thoroughly, steady deformation zone(SDZ). Based on the deformation and mechanical feature,loosen deformation zone can be divided into five layers, which are bending subside layer, densified layer, lax layer, heading face layer, and basement layer.Based on those concepts,the stabilization analysis model for loosen layer of shallow tunnel in soft soil is established, and the equilibrium condition of overlying stratum structure of shallow tunnels is presented; beneficial explanation,which is about the essential connotation of shallow tunnel construction method especially how to ensure stabilization of the working face of shallow tunnel,is given too. All of these are useful for practice and theory.