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垃圾填埋场中间覆盖层在垃圾分区或分层堆填作业过程中用于临时封闭垃圾堆体、控制降雨入渗并减少蚊蝇滋生和臭气等.常用的高密度聚乙烯(high density polyethylene,HDPE)膜作为中间覆盖层,存在易被垃圾刺穿导致坡面雨水大量入渗和造价较高等问题.我国西北地区气候干旱且黄土分布广泛,这些黄土是当地制作垃圾填埋场中间覆盖层非常便利的材料.对黄土中间覆盖层的夯实施工、防渗性能和历经干湿循环作用后开裂导致其渗透系数增大、防渗性能劣化进行了试验研究.结果表明:黄土的饱和渗透系数随干密度增大而增大,当干密度达到1.60 g/cm3时其渗透系数为10-7～10-6cm/s,防渗性能较好;现场双套环原位实验测得黄土饱和渗透系数为8.37×10-8cm/s,较室内试验大1倍左右;黄土层历经自然干湿循环作用后易开裂,有裂缝条件下其饱和入渗系数为1.18×10-6cm/s,比无裂缝条件下的增大了14倍左右.在增设15 cm厚的保护植被土层后,黄土的开裂情况得到明显抑制.
The landfill middle cover is used to temporarily close the landfill, control rainfall infiltration and reduce the breeding of mosquitoes and foul odors, etc. in the process of waste subdivision or stratification.Commonly used high density polyethylene , HDPE) film as the middle cover, there is a problem that a lot of infiltration and high cost of rainwater are easy to be pierced by rubbish.The climate in northwest of China is very dry and the loess is widely distributed. These loess is the local intermediate layer of landfill Very convenient material.Experimental research on the compaction, impermeability and cracking of middle layer of loess resulted in the increase of the permeability coefficient and the impermeability of the impervious layer after the wetting and drying cycles.The results show that the saturated hydraulic conductivity When the dry density reaches 1.60 g / cm3, the permeability coefficient is 10-7 ~ 10-6cm / s, and the seepage prevention performance is better. The on-site double-loop experimental results show that the saturated permeability coefficient of loess Is 8.37 × 10-8cm / s, which is about 1 times larger than that in the laboratory. The loess layer is easy to crack after natural wet-dry cycles, and the saturated coefficient of infiltration is 1.18 × 10-6cm / s under the condition of crack, Condition Increased about 14 times.After the addition of 15 cm thick protective layer of soil, cracking of loess was significantly inhibited.