Damage Identification Method for Tunnel Lining Based on Monitoring Stresses Data

To concrete structures, the defects such as cracks in this porous-full material are generated naturally. In service life, these defects in tunnel lining concrete will develop to damages under the effect of carbonization, steel corrode, high water pressure, permeability, etc. Incontrovertibly the generation, development and accumulation of these damages will give deterioration to the performance of the structures in service life. The speciality of the tunnel lining structure vary with that of ground structure determines that the normal damage identification method to ground structure such as bridge, building, chimney etc. is not suit for tunnel lining damage identification. Considering of damage expression, material damage model, and damage identification, here a new approach is proposed for damage identification using monitoring stresses data. In this approach, the expression of forces, stresses, and strains under loads is got through analytic method. Considering of possible damages in tunnel lining structure, using substance damage expression and stress damage expression to concrete structure, the difference values of forces, stresses, and strain can be got between those from analytic calculation and those from local monitoring. These values are used as error function; we can get the minimum value through comparing each other. The minimum value of the error function is the representative of damaged state of the lining structure. Then the integral damage and the damage level of the structure can be identified.