Monitoring of railway prestressed concrete viaducts towards long term deformations of concrete

摘要

For the construction of the first new line TGV Paris-Lyon (opened in 1981), the SNCF has built large viaducts in prestressed concrete, which have an excellent behaviour by the precautions taken during the phase of design and realization, and in particular by specific dispositions taken concerning high speed effects. Among those precautions, we notice : the weighing and the setting of the bearing reactions after the construction of the deck, the grouting control of prestressing tendons by gamma ray and the control of support level. Although a visual inspection rigorously carried out during the visits or inspections provides a precious information in order to know the state of construction from a qualitative point of view, the SNCF decided to set a monitoring by extensometers (strain sensors) in order to control the strains and the stresses of deck structures highly loaded. For the next TGV new lines (Atlantic, North, Interconnection, Rhone-Alps), the SNCF has installed, in addition of strain sensors, reactions measuring cells under the bearing devices. This monitoring wasn't exploited systematically (manual measures, instability and reliability of the instruments and of the data collection apparatus).