Influence of curtain parameter spatial variability on dam foundation seepage field considering regional heterogeneity

Seepage is a critical factor affecting safety and stability of dam foundations in hydraulic engineering. Anti-seepage curtain is an important measure to control seepage field in dam foundation. Due to the influence of construction quality and operating conditions, the parameters of the anti-seepage curtain inevitably exhibit spatial variability. The parameters spatial variability directly affects seepage field distribution and seepage control effectiveness in the dam foundation. This paper investigates influence of the parameters spatial variability of anti-seepage curtain on the seepage field of dam foundation. Firstly, a non-stationary random field discretization method considering regional heterogeneity in characteristics of the anti-seepage curtain is proposed by combining decomposed Karhunen-Loève (K-L) expansion and Sequential Gaussian Simulation (SGSIM) method. In order to consider regional heterogeneity in characteristics of the anti-seepage curtain that caused by the actual construction quality, the anti-seepage curtain is divided into three regions according to permeability coefficients difference obtained by borehole data. The decomposed K-L expansion method is employed to generate parameters random fields considering the regional heterogeneity by defining parameters mean in different regions. The SGSIM method is used to modify the parameters statistical characteristics of the borehole area to match the local parameters of borehole area with borehole data. Then, the influence of the parameters spatial variability in the anti-seepage curtain and stochastic field parameters on the seepage flow rate and hydraulic gradient mean of the dam foundation is discussed. The results indicate that the proposed parameters spatial variability simulation method could effectively characterize the non-stationary random field characteristics of the anti-seepage curtain permeability parameters. The spatial variability of the permeability parameters would not significantly change the distribution pattern of the seepage field in the dam foundation, but it has a significant impact on the statistical characteristics of the seepage field evaluation indexes, especially in the area near the anti-seepage curtain.