北京牛口峪污水水库喀斯特渗漏问题研究

位于北京西南57km的牛口峪水库建于奥陶系喀斯特化石灰岩之上。沿着区域性断层强烈的喀斯特作用使得水库发生严重渗漏,并污染了地下水体。根据水文地质条件和对水库渗漏的研究,可得出如下结论:1.牛口峪水库地区石灰岩含水体的特征主要受到牛口峪坡立谷演化过程的控制。地表下5—10m是喀斯特强烈发育带,但是充填在喀斯特裂隙中的红粘土降低了石灰岩含水体的导水性和储水能力。深于地表以下10m处,主要为裂隙含水体。石灰岩中的溶蚀裂隙和小管道沿着F_2断层发育。2.石灰岩含水体中存在着受库水影响较大的浅循环潜水流和深循环裂隙扩散流。3.牛14孔和牛11孔分属于两个水文地质单元,库水向牛11孔方向渗漏的可能性很小。4.库水主要通过表层灰岩体结构遭受破坏的石灰岩裂隙进行渗漏。最主要的渗漏带是牛14孔—牛10孔—马刨泉带,其次是水库—牛7孔—马刨泉带和四副坝坝基渗漏。主坝坝基深层石灰岩体中的渗漏是存在的,但不严重。

STUDY ON THE KARST LEAKAGE PROBLEM OF NIUKOUYU RESERVOIR, BEIJING

The Niukouyu reservoir, 57 Km to the southwest of Beijing, was built on the karstified Ordovieian limestone. The strong karstification along the regional faults makes the reservoir serious leakage that has caused the groundwater polluted. According to the study on the hydrogeological conditions and the leakage of the reservoir, the conclusions have been drawn as follows: 1.The characteristics of limestone block bearing water in the Niukouyu reservoir area is basically controlled by the evolution process of Niukouyu polje. The zone 5-10 m below the groundsurface is karstified strongly. The red clay filling in the karstic fissures has decreased the transmission and the storage capacity of the water-bearing block of limestone. The zone 10 m below the surface principally is the fissured block bearingwater. The fissures and small conduits in limestone are well developed along the fault F2. 2.There are the phreatic flow which shallow cycles and fissured diffusion flow deeply cycling, both are effected more or less by the reservoir water existed in the water-bearing block of limestone. 3.Boreholes N14 and N11 separctely belong to two different hydrogcological units, the possibility of leaking from N14 to N11 is very small. 4.Reservoir water leakes dowm to the water-bearing block of limestone through the fissures where the limestone system has been destroyed. The main leakage zones are reservoir-N14-N10-Mabao spring, reservoir-N7-Mabao spring and under the base of the complementary dam No.4. The leakage through the deep limestone aquifer under the main dam is not very serious.