The spatial variability of the groundwater inflow was mapped in detail over the tunnel wall of a test section in the Kamaishi mine (Japan) by using a evaporation sensor newly developed. Two air-tight walls were constructed at both ends of the section. Groundwater seeping into the test section was wholly evaporated for the measurement by flowing warm and dry air Into the section. Transient change of the evaporation rate during the test period were measured at 12 points on the wall. The evaporation rate over the whole surface was 5–10 mg/m2/s. Some spots of high evaporation rate, seemed to be special seepage ways (channels). were found along some major fractures.
Le degre de variation spatiale du flux de la nappe d"eau souterraine a ete clairement examine dans une section-test du mur du tunnel de la mine de Kamaishl au Japon, par l"utilisation d"un nouveau sensor A evaporation, Deux murs d"air ont d"abord ete installes a chaque extremite de la section consideree. On a fait s"evaporer l"eau souterraine qui avait coule dans la section-test pour les mesures, en insufflant de l"air chaud et sec dans cette derniere. Les changements passagers du degre d"evaporation et de temperature pendant la duree de l"experience ont ete mesures en plusiers point de la surface du mur. Le degre d"evaporatlon sur la totallte de la surface etalt de 5 a. 10mg/m2/s. Certaints endroints montrant un degre d"evaporation eleve sembialent être des conducteurs (canaux), ils ont ete reperes le long des failles importantes.
Unter Verwendung eines neuentwickelten Verdunstungs-Meßfuhlers wurde ImTestabschnitt eines Schachtes der japanischen Grube Kamaishi eine Detailkartierung der raumlichen Variabilitat der Grundwasserzuflußraten durchgefuhrt. An belden Enden des Untersuchungsabschnittes wurden jeweils luftdichte Wande installiert. Fuer die Messungen wurde das dem Testabschnitt zufließende Grundwasser mittels flleßend warmer und trockener Luft quantitativ zum Verdunsten gebracht. An mehreren Punkten der Wandoberflache wurden wahrend der Testperiode die Anderungen der Verdunstungsrate sowie die Temperatur gemessen. Über die gesamte Schachtoberflasche bet rug die Verdunstungsrate 5–10 mg/m2/s. Einige punktuell festgestellte erhöhte EvaporatIonsraten deuteten auf besondere Wegsamkeiten(Kanale) hin und befanden sich im Bereich größerer Bruche.
The spatial distribution of the Inflow rate over the tunnel wall Is an essential Information In study- ing the groundwater flow around a tunnel. However, it is not so easy to measure the inflow rate at an arbitrary point on the wall when the tunnel is excavated in a low permeable rock mass and the inflow rate is very low. The evaporation measurement is an effective tool for measuring a small inflow rate from the tunnel wall. The present authors have developed a new equipment by which small evaporation rate from an arbitrary point on the wall can be easily measured (Watanabe, et al. 1989. Watanabe et al. 1990(a), Watanebe et al. 1990(b),Watanabe 1991).In this paper, the transient change and the spatial variability of the evaporation rate measured by using the equipment in a test section in the Kamaishi Mine, Japan is reported.
The evaporation measurement was carried out in the test section constructed In a tunnel of the Kamaishi Mine. Japan. The locality of the mine and rough geometry of the ground surface near the test section are shown In Figure 1. The cross-sectional area of the tunnel is 2.5mx3.0m.
