報告書番号

N07042

タイトル（和文）

閉鎖後の堆積岩海底下坑道での再冠水速度に関する調査

タイトル（英文）

An investigation on groundwater recovery rate within sub sea floor tunnels at closed coal mines

概要 （図表や脚注は「報告書全文」に掲載しております）

海底下炭鉱閉山後の坑道水位を把握するために，池島炭鉱，釧路炭鉱において冠水位を測定した．池島炭鉱は2002年11月に閉山し，釧路炭鉱は2003年1月に海底下深部の掘削を中止した．池島炭鉱の地下水位は1年11ヵ月で405m上昇した．池島炭鉱の立坑の再冠水速度を利用して算出された立坑全体の透水係数は10-8m/s～10-6m/sとなった．一方，釧路炭鉱の冠水位はガスの流量を計測しながら一定圧でチューブにガスを注入した場合，海岸から4.7km沿岸海底下の坑内は閉山後2年経過しても冠水していないことと，5.3km付近において天盤が崩落した可能性が得られた．

概要 （英文）

The groundwater recovery rate investigated at the closed coal mines extended within sub sea floor tunnels. The Ikeshima and the Taiheiyo coal mine companies exploited the deep coal-bearing strata beneath the ocean. Ikeshima coal mine, excavated S.L. -650m to 6km offshore from Ikeshima island, was closed at November 2002, and Taiheiyo coal mine, excavated S.L. -720m to 9km offshore from Hokkaido, was stopped to excavate from the deep area at January 2003.
After closing and stopping of development, we began the investigation of the groundwater recovery rate at both coal mines. The groundwater level of Ikeshima coal mine raised +405m per 1.8 years at the main shaft. The permeability coefficient estimated between 10-8m/s and 10-6m/s to use the water recovery rate at the shaft.
Otherwise, at Taiheiyo coal mine, we measured the air pressure in tubes used by 3.5km 2.5km, and 1.5km length 2mm diameters tubes to estimate the groundwater recovery level at the 3.2km offshore plug site. Groundwater didn't reach 4.7km (1.5+3.2km) area until November 2004. There were breakdown of shotcleate and rock mass from the roof of tunnel at 5.3km from offshore line.
In this paper, we try to show the groundwater recovery rate of these sub sea floor collieries.

報告者

キーワード