| Karst landforms are widely distributed in China,and most of them are located in the southwest.Minorities gather in this area,water conservancy infrastructure is very weak,and the geological conditions in this area are very complex,karst is very developed.The key to the success of water storage in these areas is to stop leakage and prevent seepage.The water conservancy and hydropower projects under construction or to be built in karst areas are facing the problem of seepage control in karst areas.This paper takes Seven Star reservoir project in the southwest of Guizhou Province as an example,which is a typical karst landform,karst and underground river development.In the process of project research,combined with the special complex geological conditions in the reservoir area,different anti-seepage technology methods are adopted respectively,and the technology of drilling exploration hole and CT penetration,geological radar and underwater sonar are combined to find out the location,shape and scale of underground river,and the drilling of large hole for grouting mortar and double liquid slurry is used to block the large karst cave,as well as underwater The non dispersive concrete technology is used to block the underground river and other schemes to achieve the purpose of reservoir formation and water storage.The main research results are as follows:(1)The following pipe drilling method is used for large-diameter drilling and burying flower pipes in the karst cave section to ensure that the follow-up backfilling of large karst cave cavity can be carried out continuously and is not easy to be blocked.In the process of karst cave backfill,high flow concrete is used to fill,which solves the problem of backfill material fluidity,and has the conditions of large-scale production.(2)For the grouting of the impervious body around the large karst cave,the quick setting paste slurry and cement water glass slurry can be used to precisely control the fluidity and diffusion of the slurry.The strength and permeability of the slurry can meet the long-term operation requirements of the reservoir after it is combined with the sediment and other fillings in the cave.(3)By using the joint exploration technology of drilling exploration holes,CT penetration,geological radar and underwater sonar,the precise survey of the location,shape and scale of underground river is realized.It not only ensures the accuracy of finding out the location,shape and scale of the underground river,but also avoids the waste disposal caused by a large number of excavation,which has a significant effect on energy conservation and emission reduction.(4)Based on the "large bore hole pouring underwater non dispersive concrete technology and the construction method of river closure on the axis of anti-seepage curtain",the problems of large buried depth,large section,high head pressure and large flow of underground river are effectively solved,and a series of problems such as large excavation volume,large diversion strength in flood season and tight construction period are avoided.(5)By studying the layout,monitoring method and monitoring data analysis of the reservoir monitoring system in karst area,it provides a feasible reference for the layout of the reservoir monitoring system in karst area.The seepage control problem of reservoir construction in karst developed area is always a hot and difficult problem in water conservancy engineering,which has great practical significance and theoretical value,and has a broad application prospect.In this paper,through the research of underground karst seepage control technology and monitoring system of Seven Star reservoir irrigation project,it provides direct theoretical reference and guidance for the design,construction and management of similar projects. |
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