清华洞暗河堵洞成库与防渗技术

为解决富宁县城供水及其附近乡村农业灌溉问题,对清华洞暗河进行堵洞成库。水库设计总库容9934万m3,堵洞体高87.5m,最大蓄水深约116m。地质调查发现,库盆及四周均分布有较完整的相对隔水层、隔水层,山体雄厚,泉点出露均高于水库设计蓄水高程,但是,枢纽区地质构造较为复杂,岩溶发育,暗河进口左岸有溶洞和断层溶塌体分布,引起绕坝渗漏的可能性很大。根据枢纽区工程地质条件,选择附近有D3g隔水层分布并能避开溶洞影响,同时距暗河进口较近而利于施工的0+085坝址段对清华洞暗河进行封堵,并采用上下两层悬挂式半封闭帷幕灌浆对溶塌体和其他岩溶裂隙通道进行防渗处理。经多年实践表明,本防渗技术可行,坝址、防渗帷幕灌浆线路以及灌浆设计合理,水库造价低,有效地解决了县城供水和下游2.26万亩农田及21.5万亩热区作物灌溉问题。 

Reservoir building by cave-plugging and the seepage-proofing technique in the Qinghuadong uder ground river

In order to solve the problem of water supply for the Funing County and irrigation of the surround- ing rural farmlands, a reservoir is built by plugging the Qinghuadong underground river. The designed ca- pacity of the reservoir is 99.34 million cubic meters, blocking body is 87.5 m in height, and the largest im- poundment depth is about 116 m. Geological survey proves that there are relatively complete relative-imper- meable strata and impermeable strata around the reservoir basin, and the elevation of all spring outcrops is higher than the designed water-storage level. But the geologic structure at the central part of the reservoir is quite complicated and karst is quite developed, and there is cave and fault collapse-body on the left bank near the entrance of the underground river, which easily leads to leakage around the dam. According to the engi- neering geological conditions at the central part, the 0＋085 damsite is arranged in the D3 g impermeable lay- er, where the impact of caves can be kept away and is good for construction for the site being close to the riv- er＇s entrance. Furthermore, seepage-proof engineering is conducted to the leakage passages formed by the collapse bodies and the karst fissures with the upper and lower half-closed hanging style curtain grouting. Years of practice shows that the seepage-proof engineering is feasible, the seepage-proof lines and grouting design of the dam site is reasonable, and the cost of the reservoir is low. The seepage-roof engineering effectively solved the county water supply and irrigation water for 22 600 mu of farmland 215 000 mu of tropical crop downstream.