Abstract: Compound geomembrane is an effective measure for the seepage control of reservoir in plain area. In this research, numerical simulation and field test are employed to analyze the anti-seepage performance of geomembrane for plain reservoir. A finite element analysis model of geomembrane seepage is established based on the differential equation of saturated-unsaturated seepage. The Qingyuan Lake Reservoir in Shandong Province is taken as a case study. Comparison between simulation result and measured result shows that non-saturation region increases significantly in the presence of geomembrane. The non-saturation region should not be ignored, otherwise the calculated results of leakage flux, seepage line, as well as overflow point height would be lower than measured result, which makes engineers underestimate the severity of seepage. Moreover, factors of geomembrane defect (such as location, size, number and contact situation with the under layer) also have large impact on fluxes and seepage lines. Geomembrane defects mainly depend on the construction quality, so it is very important for the safety of the reservoir to control the geomembrane defects strictly.

Key words: plain reservoir, geomembrane, finite element analysis model, defect-induced leakage, seepage line