Application Of The Technology Of Combined With Cut-off Wall And Curtain In Deep Overburden Layer

Present building the dam in a complex overburden, the technology of seepage control commonly used in vertical, and its main forms:cut-off wall, curtain grouting, and Cut-off combined with curtain In a project of seepage,used the cut-off wall when the depth of the deep overburden layer less than 100 meter; the other we take the technology of cut-off combined with curtain.Because the technology of cut-off combined with curtain rely mainly on their respective cut-off wall and seepage curtain technical specifications and experience to design and construction now, and no existing technical specifications for cut-off combined with curtain, so there are still some important issues worth studying. For example:how to determine the cut-off wall and the seepage curtain, how to determine the grouting under the wall, how to prevent the hole pipe being curdled, how to determine the ratio of slurry and the conditions that change the ratio of the slurry, how to determine reasonable parameters of the grouting process, how to identify the mostoptimal injection pressure and the principles of control; how to check the quality of grouting in a drill hole that the upper part of the inspection hole filling is empty; such as how to determine the length of lap.In this paper, combining the engineering characteristics of curtain grouting under cut-off wall in the deep overburden, research suitable filling material,the corresponding optimal mixture ratio,and the grouting process; based on selected impervious materials, construction machinery, construction technologyand processes, change the ratio of slurry, filling pressures, flow control, slurry change, change the way and method of grouting to experiment, at last to inspect and analysis the effect of the grouting body.Base on the experiment of grouting under the wall in river corridor (Stake 0 +146.00m～0+172.00m) of the seepage prevention of dam founda of Luding hydropower that control by Ltd of hydroelectricfoundation of China in the Dadu River in Sichuan Province.combine with the results of the seepage prevention that the Three Gorges one and second-phase cofferdam,Falls Hydropower Station in Sichuan Sichuan Yele hydropower,Xiabandi hydropower Project,reservoir of Nishan, comprehensive analysis the performance of construction and the effect of the curtain body. put forward with the formationimpervious impervious superior performance technology that adapted to the conditions of layer, as well as supporting the construction of technology and technology;Comprehensive analysis the research results, proposed the economical and safe program of the seepage prevention of dam founda; proposed the method for determining the length of lap; proposed a grouting method under the cut-off wall; proposed the size ratio, grouting pressure, flow control, slurry conversion conditions, the end of the standard and methods of determining special circumstances; proposed a method to check the quality of grouting in a drill hole that the upper part of the inspection hole filling is empty.