Abstract
Hydrogeochemical investigations were carried out for the water appeared in some pilot tunnels which were under construction in granite regions. The samples obtained are, in general cases, falling water near the cutting face of pilot tunnel and, in another cases, flowing water from horizontally drilled holes for prospecting fissure water. Such water is considered to be conducted through networks of open discontinuities and fault-sheared zones developed in granitic rock masses above and around the pilot tunnels. Cations, anions and other dissolved substances are analysed throughout the investigations. Data of hydrogeochemical analysis are compared with each other and with stream and spring water distributed above and around the tunnelling sites. As results, the authors pointed out that mineral water, defined as higher contents of Cl-, HCO3-, SO42- ions, is distinguished among the water obtained. Mineral water and common water are concealed irregularly and alternatively within the fault-sheared zones. Results of TR (tritium ratio) measurements indicate that large portions of above-mentioned falling water is supplied from the rainfalls before 1955 A. D., but some parts are recharged from the rainfalls after 1955 A.D. So, “intrusion” of rain water is rapid successively to the construction even though the case of pilot tunnel. In one case, 10-1 order's TR-value is measured from the cutting face of the central part of the Enasan tunnel.
