Research On Deformation And Methord Of Health Diagnose Of Operational Subway Structures In Soft Soil

Shield tunnel isa kind of fabricated structure composed by segments with longitudinal and transversal bolts. Shield tunnels embedded in soft soil will produce obvious uneven longitudinal displacements and transversal convergence during operation due to variable cooperation of geologic condition difference, constructions of deep foundation adjacent to the subway, and periodic vibrations of moving trains. This deformation gives bad effects in the aspects of carrying capacity and tunnel service and makes the tunnels health condition deteriorate.How to select the health parameters and diagnose model suitable for the characteristics of soft soils and shield tunnels and then give credible and reliable evaluation for operational tunnels are the main objectives of this work. And the detailed contexts are as follows:1. Reasons of uneven settlements for the tunnel segments are summarized and analyzed based on the on-site monitiong data and FEM software;2. 3 degree B-Spline curve is chosen to fit the longitudinal settlement curves, which solves the problem of curvature continuum for joint notes due to its continuous second derivative vector and overcomes the efficiency and accuracy of computing curvature with 3 points by hand. And the relations between longitudinal curvature and bolt tensile stress, differential settlement and bolt shear strength are deduced;3. The transversal convergence curves are also fitted with 3 degree B-Spline function. Transversal deformation ratio is put forward to evaluate the degree of deformation based on curvature radius of the deformed curve. And the relations between transversal deformation ratio and bolt tensile stress are deduced;4. The damage detection method of tunnel structure in soft soils based on curvature is put forward and the damage level of shield tunnels is given. And health index, health level and health diagnose model special for shield tunnels in soft soils is put forward on the basis of fuzzy synthesis evaluation, analytic hierarchy process (AHP) and pattern recognition theory.5. The subway of Shanghai No.2 metro operation line is diagnosed to test and verify feasibility of the model.