Study On The Sensitivity Of Seepage Flow In Aging Dams

In consideration of the aging of impervious curtain and the reclamation and expansion of crack of dam body and their influence on the seepage flow of the aging dams, the mathematical and mechanical knowledge, such as seepage FEM, artificial neural network, probability statistics, together with the knowledge of dam engineering, are introduced into this dissertation. The mathematical monitoring model of seepage flow, the sensitivities of .the impervious curtain to the seepage flow of dam foundation and the crack to the seepage flow of dam body, the methods of determinating the monitoring indices and distinguishing the abnormity of the seepage flow are researched separately. The main contents are as follows:1. Based on the analysis of the hysteresis effect of water level and rainfall on the seepage flow, the monitoring models of seepage flow of aging dams are researched, and the seepage statistical model based on hysteresis effect is established. In addition, the neural network model with non-linear mapped capacity is established, and the influence degree of the environment data on the observation data is estimated comprehensively by using the power value.2. Using the numerical test method of the 3D-FEM of seepage flow, the sensitivity of the impervious curtain working status to the seepage flow of dam foundation is researched by changing the permeability coefficient of the curtain. The influences of the permeability coefficient k on uplift pressure reduction factor a and on the seepage discharge of grouting gallery Q are analyzed. Accordingly, the expressions of k and a -. k and Q are obtained.3. The determination of permeability coefficient k and the equivalent width of crack is discussed. The sensitivities of the crack working status and head difference AH to the seepage flow of dam body are researched by using the numerical simulation method. The influences of the permeability coefficient k and head difference AH on the seepage discharge of crack are researched, and the expressions of Q and k, AH are obtained.4. The methods of determinating the seepage monitoring indices, such as general method, confidence region method, little probability method, are discussed. The abnormity of the seepage flow of the aging dams is distinguished by time-dependent exponent together with monitoring indices.