降雨形式对毛细阻滞覆盖层防渗性能的影响研究

Influence of rainfall patterns on anti-seepage performance of capillary barrier covers

毛细阻滞覆盖层的防渗性能对于控制渗滤液和减轻垃圾填埋场周边环境的污染具有重要意义,因此得到广泛研究。前人在研究中多采用恒定降雨强度来模拟降雨气象条件,而对降雨形式对毛细阻滞覆盖层防渗性能的影响关注较少。因此,采用自主研发的土柱降雨入渗试验系统,分别对短时强降雨和长时弱降雨两种降雨情况下,降雨形式对毛细阻滞覆盖层防渗性能的影响开展了研究,并揭示了最不利降雨形式。同时,采用SEEP/W软件对各试验工况进行数值模拟,以使模拟结果与试验结果能够相互印证。研究结果表明:试验结果与模拟结果基本一致,最大误差不大于3%;在短时强降雨情况下,降雨形式仅对覆盖层上部的体积含水率和孔隙水压力有较大影响;而在长时弱降雨条件下,降雨形式对整个覆盖层的体积含水率和孔隙水压力均有显著影响;降雨形式对覆盖层突破时间及渗漏量均有影响,前锋型降雨的突破时间最短,产生的渗漏量最大,后锋型降雨的突破时间最长,产生的渗漏量最小;前锋型降雨更易造成覆盖层突破失效而产生较大的渗漏量,为最不利降雨形式。该研究结果可为毛细阻滞覆盖层设计提供参考依据。

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.