白岩洞地下河洞穴系统及其开发方案的优选

THE CAVE SYSTEM OF BAIYANDONG UNDERGROUND RIVER AND ITS OPTIMAL EXPLOITATION

:白岩洞地下河洞穴系统位于保靖县城东南 7km,为一个复杂的现代地下河型洞穴系统。白岩洞洞穴系统由主洞道和吉库、两岔河、三岔河和铁匠洞等 4条主要支洞构成。主洞道分为白岩洞入口 -三岔河、三岔河 -金塘湾洞冒水处和金塘湾洞冒水处 -金塘湾洞 3段 ,长约5151m,高差 10 4 m,坡降 2 0‰。金塘湾洞冒水处 -金塘湾洞只有一条支洞 ,洞道结构相对简单 ,最枯流量 2 7l/ s(1999年 2月 2 9日 ) ,高程36 3m,能够满足与目前最低的灌溉渠道 (350 m高程 )联网要求。因此 ,建议在金塘湾洞引水 ,设计隧洞长度 330 0 m,取水高程 36 3m ,出口高程352 m。

WT5BZ]Baiyandong underground river cave system is located 7 km southeast to Baojing County. It embraces one main corridor and four major branch galleries, i.e. Jiku,Liangchahe, Sanchaghe and Tiejiangdong. Th main corridor, with a total length of 5151m, an elevation balance of 104m and a hydraulic gradient of about 20‰, is divided into three parts, that is, Baiyandong entrance Sanchahe, Sanchahe the water emergence of Jintangwan and the water emergence of Jintangwan Jintangwan galleries. The first part has three offshoot galleries and the third part only one. The second part is not accessible. River flow was monitered for one year. The results show that the Sanchahe had minimum discharge of 16.8 l/s at 397 58m elevation and the Jintangwan 27.0 l/s at 363m elevation in dry season of 1999. Local people have been aspiring to exploit the underground river for long. In 1970s, an underground dam was built at the confluence of the main current and the Tiejiangdong tributary so as to form a karst depression reservoir in Tiejiangdong depression. This project was unsuccessful because of leakage from under dam. In 1997, three versions of tunnelling project were put forward by the Baojing Bureau of water Concervancy. The first version considered a 1480 meter's long tunnel with water intake in Liangchahe and water exit at elevation 428.00m and 427.20m a.s.l. respectively. The second one, 2450 meter's long tunnel with water intake in Sanchahe and water exit at elevation of 397.0m and 395 0m a.s.l. respectively. The third one, 3580 meter's long tunnel with water intake also in Sanchahe and different water exit at elevation of 396.00m and 392.90m a.s.l.. The study conducted in the past two years leads the authors to the conclusions: tunnelling has an advantage over damming and the three proposed versions of tunnelling do not take full advantage of the discharge of the river. The authors suggest a new version in Jintanwan gallery with a tunnel of a length of 3300m and elevations of 363.00m and 352.00m a.s.l. at water intake and water exit. This version is justified in obtaining the biggest discharge, using a simple cave passage and arranging the water exit at an elevation of 352m, which can meet the need of networking with the lowest 350m irrigation ditch.