云南压实黏土层对油类污染物的防渗性能实验研究

目前在压实黏土层(CCL)应用于油类污染物的防渗工程设计中，以水在CCL中的渗透系数低于10-7 cm/s为依据，该依据可能存在偏颇。文中以0#柴油和93#汽油作为典型油类污染物，在云南CCL中进行油相水相交替渗流实验。结果表明：(1)不同渗透压力下，水在云南CCL中的渗透系数为(0.41~2.52)×10-8 cm/s，云南黏土压实后可作为天然防渗衬层。(2)0#柴油和93#汽油穿透饱水的云南CCL时，存在临界水力梯度，分别为0.05和0.02 MPa；一旦突破临界水力梯度，CCL的渗透性急剧增大，0#柴油和93#汽油在CCL中的渗透系数较水在CCL中的高出1~3个数量级。(3)水相驱替0#柴油和93#汽油的过程中，CCL的渗透系数为10-7～10-6 cm/s；被油浸透过的CCL不能继续作为防渗衬层使用。(4)针对油类污染物的CCL防渗工程设计，以水在CCL中的渗透系数低于1.0×10-7 cm/s为标准是不适用的，需要提高CCL防渗的设计等级。

Anti-seepage performance for oily pollutants in compacted clay layer of Yunnan Province,China

In the current design of anti-seepage projects using compacted clay layers (CCL) against oily pollutants, the criterion that the hydraulic conductivity of water in CCLs should be less than 10-7 cm/s may be abused. In this paper, we performed oil (0# diesel and 93# gasoline) and water alternate seepage through CCLs of Yunnan Province, China. The results show that (1) under different seepage pressure, the hydraulic conductivity of water ranged (0.412.52)×10-8 cm/s, indicating the Yunnan clay can be used as natural anti-seepage lining; (2) critical hydraulic gradients for 0# diesel and 93# gasoline seepage through water-saturated CCLs were 0.05 and 0.02 MPa, respectively; once the critical hydraulic gradient was broken, the permeability of CCL increased rapidly and hydraulic conductivity of oily pollutants was 13 orders of magnitude higher than that of water; (3) in the process of water seepage through 0# diesel or 93# gasoline filled CCLs, the hydraulic conductivity of water was (10-710-6) cm/s; oil-soaked CCLs could not serve as anti-seepage lining again; and (4) the current standard for anti-seepage design against oily pollutant requires that hydraulic conductivity of water in CCL to be less than 1×10-7 cm/s, which is not applicable; the level of CCLs anti-seepage performance should be improved.