Abstract: The anti-seepage performance of capillary barrier covers (CBCs) has been widely studied because of its importance in controlling leachate and mitigating pollution in the surrounding environment of landfills. However, the effect of rainfall pattern on the anti-seepage performance of CBCs has often been neglected in previous work because the constant rainfall intensity is usually used to simulate rainfall. Therefore, this study investigates the effect of rainfall patterns on the anti-seepage performance of CBCs and reveals its most unfavorable rainfall pattern under two types of rainfall conditions, namely short and heavy rainfall (SHR) and prolonged light rainfall (PLR), by using the self-developed soil column rainfall infiltration test system. In addition, the SEEP/W software was used to numerically simulate each test condition so that the simulation results and the test results could corroborate each other. The results show that the test results are basically consistent with the simulation results, and the maximum error is no more than 3%. The rainfall pattern only has a significant effect on the volumetric water content and pore water pressure in the upper part of the CBCs for SHR, while for PLR, the rainfall pattern has a significant effect on the volumetric water content and pore water pressure of the whole soil column. The rainfall pattern has an effect on both the breakthrough time and the leakage amount of the CBCs. The breakthrough time of the advanced rainfall is the shortest and the leakage amount is the largest, while the breakthrough time of the delayed rainfall is the longest and the leakage amount is the smallest. Advanced rainfall is the most unfavorable rainfall pattern, which is more likely to cause the CBCs breakthrough failure and produce large leakage. The research results can provide a reference for the design of CBCs.

Key words: capillary barrier covers(CBCs), rainfall infiltration, rainfall patterns, anti-seepage performance, numerical simulation