Study Of Seepage Deformation Theory And Method Of Leakage Detection Of Dyke Foundation

On the basis of analyzing and summarizing previous penetration theory and seepage deformation and method of seepage detection, this paper puts forward the theoretical model of seepage deformation and the planar heat source method for seepage detection. And also, environmental isotope and hydrogeochemistry are applied to the analysis and evaluation of the seepage of the dam foundation.The seepage and boiling of sand on the uniform isotropic gravel base of dam can be reduced to completely penetrating well and nonpenetrating well model. While the gravel layer is thick, the occurrence and development of the boiling of sand correspond to the model of hemispheric bottom hole which cheek by jaw with upper clay band; While the gravel layer is relatively thin, the occurrence and development of the boiling of sand correspond to completely penetrating well model. By means of establishing of notional model of stratum penetrability and computational well flowing model during the development of boiling of sand, we can simulate the overall process of boiling of sand .The computational result suggest that the occurrence and development of the boiling of sand are usually in the direction which is perpendicular to the dam axis, forming the perforated collective seepage passageway. The concept of 'critical distance' is that the minimum distance between the exit of passageway mentioned above and the bank with condition of no change. If the exit is within the critical distance, perforated collective seepage passageway will form, the more closer, the more dangerous will be. Replacing the penetrability of coarse surface or the cranny near the stratum interface which has all kinds of causes of formation with the of cranny, we can form notional model and computational well flowing model for stratum penetrability which is in contact with scour developing course and simulate the overall process of contact scour. We simulate the contact scour between the clay band and the gravel. The silver sand near the interface begin flow through the seeping exit, the permeability coefficient near seeping exit first increases, then developing to the interior step by step, it can also form the collective seepage passageway. Its developing law is analogous to that of boiling of sand development with faster developing speed. We establish the completely penetrating well model for the floating earth on the doubledecked embankment foundation and model of drift sand in hemisphericbottom hole, which simulate the dynamic process of drift sand basing on the critical hydraulic slope by a example using the tune-sharing steady flow theory. The collective seepage passageway formed by seepage deformation will develop from the exit to the direction perpendicular to the dam axis, expanding on the surface from the exit to riverbed with increasing depth. The scale of passageway lies on the magnitude of discharge of the exit and the water level, and it reach the maximum at lower water level. Practice proves that the synthetical tracer method for detecting and analyzing the seepage of complicated embankment foundation is effective. And it is successful hi detecting the collective seepage passageway which come from the bedrock on the dam of North River. At the same time, this paper will introduce the planar heat source method to detect and analyze the seepage of faultage embankment foundation, which further confirm the spatial state of the faultage embankment foundation of North River Levee. Hydraulic geochemistry and environmental isotope method improve our way to analyze the seepage of complicated embankment foundation. Through three applications of specific dam engineering, some important engineering problems are solved.