Influence of large scale tunnel digging and drainage on groundwater

以松本-白山隧道为例，研究了隧道渗漏长期排水对地下水系统的影响。虽然隧道渗漏水排出1000万m~3已有24年，但~3H浓度一直保持在较低水平，氧同位素值一直很均匀。因此，隧道施工前补给的水被认为是排干了。1000万m~3隧道渗漏水仅占隧道水位至地表沉积物总孔隙度的22%。需要80多年才能完全排出沉积物中的所有孔隙水。阐明了在低湿度条件下，可以用氧同位素估算蒸发率。在Namariyama矿区大规模开采的周围，发现了高浓度的海藻用锌。堵塞的巷道排水涌上海岸，矿井巷道排水中金属含量较高。

Influence of long term drainage of tunnel seepage on groundwater system was studied at Matumoto-Shiroyama Tunnel. Although 10 million m3 tunnel seepage water has been drained for 24 years, 3H concentration has kept low and oxygen isotope values have been uniform. Therefore, recharged water before the tunnel construction was thought to be drained. The 10 million m3 tunnel seepage water was only 22% of all porosity in sediment between the tunnel level and surface. It needs more 80 years to perfect drain of all pore water in sediment. It has been clarified that evaporation rate can be estimated from oxygen isotope under low humid condition. At the surrounding of large scale digging, Namariyama mine area, high concentration of Zinc for seaweed was found. The drainage water from the plugged tunnel welled up at the coast and the drainage water derived from mine tunnel was high concentration of metal.