大宁河补水工程环境地质条件与布置方案研究(Ⅰ)

Discussion on layout scheme and environmental geological conditions of Daning River water diversion project(Ⅰ)

梳理了大宁河补水工程的设想方案及其由来,介绍了前人所做的探索。研究了工程涉及的大宁河流域大昌镇以北至堵河流域官渡口镇范围的区域地质条件,认为工程最近的区域断裂——青峰断裂距工程下游出口远,几无影响;建筑物分布区地震烈度均小于或等于Ⅵ度,区域稳定条件总体优。在前人及野外工作基础上,结合环境地质条件优化了东西数个设想方案,推算了4个相对可行方案的工程基本特征参数。结合不同部位建筑物特性与其地质环境条件,宏观分析了二者的相互影响。研究认为:大宁河剪刀峡-白鹿溪段总体稳定条件好,但对白鹿巨型老泥石流沟、神基坪黏土岩延伸的边坡稳定等危险应予重视;堵河茅草坡-官渡口段总体稳定条件好,局部潜在致灾地质体因梯级水库淹没而缓解,外流域大流量水量注入会造成本流域局部岸坡再造,但以渐进式小范围改造为主,危害小;岩溶和软岩问题牵涉面广,应予重视。

The ideas and origins of water diversion project from Daning River are reviewed, and all the previous explorations are summarized. This paper researches the regional geological conditions from the north of Dachang Town （ Daning River Basin） to the area of Guandukou Town （ Du River Basin） , and the result shows that there is nearly no influence on the project because Qingfeng fracture, the nearest regional fracture of the project, is far away from the exit of downstream ; the overall regional condi- tion is excellent because the basic seismic intensity of the area is less than or equal to VI degree. On the basis of the previous ex- plorations and field work, combining with environmental geological conditions, several schemes from east line to west line are op- timized and basic parameters of four feasible schemes are calculated. The interrelationship between the features of different parts of the project and its environmental geological conditions is analyzed macroscopically. The results show that the geological condi- tion from Jiandao Gorge （ Daning River） to Bailu Creek is generally stable, but the giant debris flow gully of Bailu Creek and the slope stability of clay rock at Shenjiping should be paid attention to; meanwhile, the geological condition from Maocaopo to Guan- dukou along the Du River is also generally stable, some local geologic body which has the potential to cause disasters is alleviated after the inundation of reservoir, partial bank slopes in the basin will be recreated due to the incoming flow from other basins, but in small scale and the danger would be small. The problems of karsts and soft rocks should be focused due to their wide distribution.