Influence of Hydrogeochemistry on Tunnel Drainage in Evaporitic Formations: El Regajal Tunnel Case Study (Aranjuez, Spain)

Many of the large number underground works constructed or under construction in recent years are unfavorable terrains facing unusual situations and conditions. This is case subject study this paper: a tunnel excavated evaporitic rocks that experienced significant karstification problems very quickly over time. As result situation, causes may underlie rapid investigated novel methodology presented civil engineering where use saturation indices for different mineral specimens present has been crucial. The drainage rock massif El Regajal (Madrid-Toledo, Spain, Madrid-Valencia high-speed train line) was studied permitted in-situ hydrogeochemical evolution water flow Miocene materials Tajo Basin as full-scale testing laboratory, conforms whole, single aquifer. work provides based on calculation activities through samples piezometers, estimating index saline dissolution capacity brine, which surprisingly high despite electrical conductivity. circulating brine appears unsaturated with respect to thenardite, mirabilite, epsomite, glauberite, halite. alteration consequent renewal aquifer by infiltration rain irrigation cause imbalance modification characteristics massif. These modifications include important loss material dissolution, altering resistance terrain increase porosity. Simultaneously, expansive recrystallization processes decrease porosity were identified work. allows these phenomena be followed time, this, turn, facilitate implementation preventive engineering.