Ventilation experiment in the Mont Terri underground laboratory

摘要: Abstract The required ventilation of the underground drifts during construction and operational phases a radioactive waste repository could give rise to process desaturation rock around drifts, changing its hydraulic thermal properties. This change properties may have an impact on design repositories (drift spacing size), which depends load that clay barrier can accept. experiment (VE) has been carried out at Mont Terri laboratory (Switzerland). Its main objective was evaluate ”in situ” better understand consolidated formation, when subjected flow dry air several months. performed in 10 m long section non-lined horizontal microtunnel (diameter = 1.3 m), excavated 1999 shaly facies Opalinus clay. In Summer 2002 (3.4 years after excavation), test sealed-off, monitored with total 86 sensors (rock water potential, content, temperature displacement, condition section). Specifically, thickness approximately 2 m, 24 piezometers, 32 hygrometers, 8 extensometers 5 electrode chains (geoelectrical survey) were installed. equipment generates ( Q ) specified values relative humidity (RH T ), is sent one ends through inflow pipe, then evacuated outflow pipe other end. Values , RH are also measured pipe. period  = 30 m 3 /h) began July 2003, phase (≈2 months) where set equal 30% another (≈5 almost  = 1–3%). After this period, finished 3-months resaturation (target  = 20 m /h  ≈  100%). most important general conclusion obtained from experiment, monitoring data modelling results, following: it be reasonably predicted that, under real conditions (relative much higher than VE test), clayey rocks low conductivity K −12  m/s) will not relevant issue. bulk characteristics practically affected by ventilation, except narrow ring wall galleries (thickness less 30 cm), degree saturation lower 95%.