On Method For Design Of Seepage Control With Impermeability & Drainage Measures In RCCDs

With the applications of the numerical procedure of nodal virtual flux, 2D element without thickness for fracture seepage, drainage-substructure technique, and switch of drainage well to strict solution to seepage problems, and on the basis of the results from the continuous research on the seepage property and seepage control method of the Longtan RCC gravity dam about 200m high for over 10years, the seepage0control mechanism and effectiveness of the seepage control system with seepage prevention structures on both of the upstream and downstream sides of RCCDs were studied in detail. The agents and problems involved are the effectiveness of the upstream and downstream impermeable structures, the weakness of the permeability of RCC matrix, the strong permeability of the interfaces and lift joints, the appearance of vertical and horizontal cracks in the upstream seepage prevention structures, the efficacy lose of impermeable measures in the transverse contraction joints between dam blocks, the diameter and spacing at centers of drainage wells, and so on.