Keywords: high speed lines, drain, clogging, calcite precipitation, monitoring, lime, sulphate, carbon dioxide, maintenance.

This paper concerns the railway infrastructure drain clogging issues linking to the high rate calcite formation at low temperature (less than 25 degrees C). Three sites on different high speed lines were investigated in order to study the geology and geotechnical impacts linked to the calcite formation process. On the main experimental site, at Chauconin, France, in situ calcite formation process was assessed on the basis of the continuous monitoring of water (pH, temperature, conductivity, etc.) and relevant forcing variables (rainfall, groundwater level, flow). Water was seasonally sampled and analyzed to verify the thermodynamic and kinetic evolution of the calcite precipitation. At the beginning of the survey, the geotechnical characteristics through the railway platform and also inside the natural soil were determined. The platform materials provide the drain water with unlimited reactants (calcium and carbonates), as well as the kinetic motors (magnesium or sulphate). For the fist time, geotechnical parameters were highlighted as calcite formation promoters in this paper, especially, the nature of the clean washed gravel and of the foundation materials, the hydraulic drop at the place of the drain junctions or the water fall at the drain outlet, the width of the water inlet.

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