Numerical simulation of performance evolution of anti-seepage curtains in the high water head tunnel surrounding rock

To study the dynamic evolution process of the anti-seepage curtain under high water head, a multi-physics coupling model reflecting the time-effect of the curtain was established based on the principles of seepage mechanics, solute migration and chemical kinetics. The model is composed of a seepage model, a solute migration model, and a curtain dissolution model, which is solved by the finite element method, and verified by combining the relevant uplift pressure monitoring data. The simulation results indicate that the porosity of the anti-seepage curtain increased by 29.38% compared with the initial porosity, and the permeability coefficient increased by 1.95 times. The dissolution of the anti-seepage curtain had the characteristics of temporal and spatial variation, the dissolution extent at the middle part is much quicker than at its bottom part, particularly, there is almost no dissolution at its top part. The dissolution area near the upstream side of the anti-seepage curtain is larger than that on the downstream side. Simultaneously, the research results and monitoring data are available to evaluate the durability of the curtain, and provide a scientific basis for the safe operation and management of the power station.