腾发覆盖垃圾填埋场覆盖层机理试验研究及结构分析

研究了腾发覆盖垃圾场覆盖层水平衡机理并探讨了植物、土质和厚度调节对控制覆盖层水均衡的作用.6组腾发覆盖试验结果表明,腾发作用在覆盖层水量平均过程中起关键作用,覆盖层土壤水分耗散与叶面积指数表现出非线性增长关系;植物生长条件下覆盖层土壤水分总耗散量可以达到无植物覆盖情况下的3.3～4.5倍,60 cm覆盖厚度、植物生长条件下能够提供97.2 mm的土壤水库容积,而无植物生长情况下有效库容仅为62.8 mm; 降雨入渗在覆盖层中表现出非均匀运动特性,流动区域随深度的增加而呈指数递减的趋势,20、40和60 mm降雨条件下最大入渗深度与平均入渗深度的比值分别为3.65、1.77和1.40,表明土壤水库容量不仅取决于覆盖层土壤质地,厚度和初始含水率,并且与降雨量有关,非均匀入渗是植物生长条件下渗沥产生的主要原因.Hydrus-2D模拟覆盖层水均衡要素动态结果显示,相比粘土,选用砂壤性土壤能够更为有效利用腾发作用的调节和控制覆盖层水分,达到控制渗沥的目的.

Field Test and Evaluation of Landfill Performance and Structure with Evapotranspiration Cover

Water balance performance of an evapotranspiration landfill was studied, considering vegetation structures, soil textile, and soil cover thickness. Results of six experiments showed that the transpiration process played an importance role in controlling water balance in the ET cover system. A nonlinear relationship was established between the transpiration amount and vegetation leaf area index. The evapotranspiration amount was 3.3 to 4.5 times as that of evaporation in the bare soil. In a 60 cm soil profile, the soil water storage capacities were 97.2 mm and 62.8 mm with and without a vegetation cover, respectively. Precipitation infiltration behaved preferentially and heterogeneously, and the preferential flow was the major contribution to percolation. The ratios between maximum and average infiltration depths were 3.65, 1.77, and 1.40, respectively, for 20 mm, 40 mm, and 60 mm of precipitation. Therefore, besides soil textile, soil cover thickness, and the initial water content, precipitation amount was an essential factor affecting the water storage capacity. Numerical simulated results indicated that using a sandy loam as the cover soil was more effective in removing water through evapotranspiration and reducing percolation than using a clay soil.