Numerical simulation on the ground deformation by Pipe-roof Pre-construction Method

It´s one of the key problems that ground deformation and influeced to the near buidings couseed by the city underground space construction. The surface deformation and vault subsidence regularity are analysed for station within the turkmen excavation to ensure the technology successful application to underground subway station in Shenyang Metro Line 2, based on FLAC^3D simulation. Results show that, (1) the surface deformation and vault subsidence could be less by using Pipe-roof Pre-construction Method in the full-section turkmen excavation, and in the whole Pipe-roof Pre-construction Method construction process of surface subsidence caused by the proportion is less too, which could meet the requirements of controlling the surface subsidence target. (2) with the great influence of horizontal loads, the underground structure in advance could partially offset the ground deformation caused by vertical loads. the surface deformation and vault subsidence tend to be stable, and the sedimentation curve rebounds a little. Pipe-roof Pre-construction Method is much better than depth-span ratio underground structure in controlling the ground deformation. (3) surface deformation and vault settlement of shallow buried underground arch shell structure were basically equal, which built by Pipe-roof Pre-construction method, and there was a phenomenon that the surface deformation was bigger than vault settlement during station within the turkmen excavation. (4) The supporting structure beforehand built by Pipe-roof Pre-construction method could almost completely replace the supporting function of the earthwork excavated to the surrounding rock. The Pipe-roof Pre-construction method deserves further research because it has no bad influence to near environment, has obviously social and environmental benefits, and can be used to build traversing urban traffic hub of the underground engineering.