Abstract:

Heavy rainfall events frequently occur in natural environments. To enhance landfill operation and management, it is essential to investigate the water infiltration characteristics of the landfill soil cover and the associated slope stability under heavy rainfall conditions. Although relevant analytical studies have been reported, they have limitations, such as the limitation to account for the continuous variation of heavy rainfall rates over time. Therefore, on the basis of the previous researches, this paper incorporates the time-varying feature of heavy rainfall rate and the arbitrary initial water content distribution form, and employs the joint methods of variable substitution, separation of variables, and series transformation to obtain the corresponding analytical solutions for water infiltration. Subsequently, the developed analytical solution is validated by comparing it with existing analytical and corresponding numerical solutions. Finally, the analytical solutions are applied to analyze the effects of heavy rainfall patterns and initial water content distribution forms on the bottom leakage and slope stability of the landfill soil cover. The results indicate that among the four heavy rainfall patterns with equal total rainfall, the “pre-peak” rainfall pattern exhibits the highest bottom leakage rate (Q_b) and cumulative leakage CQ_b, but the lowest factor of safety F_s for slope stability assessment. Conversely, the “post-peak” rainfall pattern shows opposite trends, while intermediate results are observed for the other rainfall patterns. Among the four initial water content distribution forms with equal total water storage, Q_b and CQ_b are the highest in the distribution form with low water content at the top and high water content at the bottom. However, in this distribution, F_s is the lowest after a period of heavy rainfall infiltration. Conversely, Q_b and CQ_b are the lowest in the distribution form with high water content at the top and low water content at the bottom, while the corresponding F_s is highest. Overall, this conducted analytical study offers guidance for the application and design of landfill soil covers.

Key words: landfill soil cover, time-varying heavy rainfall, water infiltration, analytical study, slope stability