渗透系数的变异性对压实黏土衬垫性能的影响

Effect of permeability coefficient variability on performance of compacted clay liners

压实黏土衬垫是填埋场等环境岩土工程中常用的屏障材料,其厚度和渗透系数是主要的设计参数。考虑渗透系数的变异性,用衬垫底部污染物相对浓度和通量等指标分析了设计参数对衬垫有效性的影响。研究表明,渗透系数的变异性对衬垫性能有很大的影响:当衬垫厚度较小或渗透系数均值较大时,衬垫底部出现高浓度(接近于1)的概率很大,这个浓度区间可能比相对浓度的均值高很多,对周围环境污染有较大的威胁。从非反应性溶质的运移来看,我国规范中对衬垫厚度和渗透系数的规定是合理的。相对于污染物的通量,厚度和渗透系数对衬垫底部相对浓度的影响更为显著,相对浓度更适合作为评价衬垫性能的指标。

Compacted clay liner is the barrier material for landfill;and its thickness and permeability coefficient are important for design.Based on performance design and probabilistic method,the effect of design parameters on contaminant relative concentration and flux at base of liner is analyzed.The variability of permeability coefficient is very significant for the performance of liner.The probability of high concentration（close to 1） at base of liner is large,even the mean concentration is relatively low.This is a big threat to environment,which can＇t be reflected through deterministic method.From the probabilistic perspective,the requirements of thickness and permeability coefficient for liner are reasonable.Relative to the flux at base of liner,the relative concentration is more sensitive to thickness of liner and should be used as the key indicator for performance evaluation of liner.