Probabilistic analysis of the performance of compacted clay liners with superficial cracks
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摘要: 压实粘土衬垫是填埋场等环境岩土工程中常用的屏障材料，其表面的干燥裂隙可能对衬垫的有效性有一定的影响。将整个衬垫分为受裂隙影响的表面土层和不受裂隙影响的下部土层两部分，把饱和渗透系数和裂隙扩展深度看作随机变量，采用蒙特卡洛法分析衬垫底部污染物相对浓度和通量的概率特征。研究表明，由于衬垫底部出现高浓度（接近于1）的概率较大，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，因此确定性方法得到的结果存在较大的风险；考虑表面裂隙导致渗透系数的增大，得到的结果更为合理；保证衬垫足够的厚度可以降低表面裂隙土层饱和渗透系数的变化对衬垫防渗效果的影响；将两层土的渗透系数看作独立随机变量，得到的结果偏于安全。Abstract: Compacted clay liner is the major barrier material for landfill. Desiccation crack on the superface of the liner may affect its performance. The liner was divided into crack part and noncrack part, and the Monte Carlo method was used to analyze the hydraulic performance of the liner. The probability of high concentration (close to 1) at the base of the liner is large, even the mean concentration is relatively low. This is a big threat to the environment, which cannot be reflected through deterministic methods. It is more reasonable to consider the increase in hydraulic conductivity for crack part. Enough thickness of liner is important to reduce the effect of hydraulic conductivity of crack part on performance of the liner. Taking the hydraulic conductivities of the two parts as independent variables, the results tend to be safe.
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Key words:
- compacted clay liner /
- crack /
- hydraulic conductivity /
- variability
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