单一裂隙优势渗流对黏土层防渗性能的影响分析  

Influence of preferential flow induced by a single crack on anti-seepage performance of clay barrier

作　　者：蔡武军[1,2] 凌道盛[1,2] 徐泽龙[1,2] 陈云敏[1,2] 

机构地区：[1]浙江大学软弱土与环境土工教育部重点实验室,杭州310058 [2]浙江大学岩土工程研究所,杭州310058

出　　处：《岩土力学》2014年第10期2838-2844,2887,共8页Rock and Soil Mechanics

基　　金：国家重点基金研究发展计划(973计划)项目(No.2012CB719805)

摘　　要：垃圾填埋体不均匀沉降等容易引起压实黏土防渗层开裂,显著降低其防渗性能。将裂隙作为高渗透性的多孔介质材料,建立了含单一裂隙压实黏土层的饱和/非饱和渗流模型,数值研究了含裂隙黏土层中的优势渗流过程,对比分析了裂隙位置、深度、宽度和渗透系数对压实黏土层水分击穿时间和稳定渗漏量的影响。结果表明,含裂隙压实黏土层的渗流过程可分为3个阶段:初始阶段、击穿阶段和稳定阶段;底部裂隙对压实黏土层防渗性能的影响较小,而顶部裂隙和贯通裂隙的影响较大;水分击穿时间随裂隙深度增大而迅速缩短,为保证黏土层防渗性能,宜将裂隙深度控制在0.1倍土层厚度以内;水分击穿时间和稳定渗漏量随裂隙宽度、渗透系数的增大而分别缩短和增加,且当其达到一定值后逐渐趋于稳定;裂隙贯通后将显著降低压实黏土层的防渗性能,其稳定渗漏量随裂隙宽度和渗透系数的增大而呈线性增长。The waterproofing properties of compacted clay barrier at landfill site will be greatly weakened by crack which is induced by the waste’s differential settlement. In order to reveal the effects of preferential flow on the anti-seepage performance of cracked barrier, the crack is treated as high-permeable porous medium, and a simplified saturated/unsaturated seepage model of the barrier with a single crack is developed to study the process of preferential flow. In addition, the influence of crack position, depth, width and permeability coefficient on the anti-seepage performance of the barrier is comparatively analyzed. The results show that the infiltration process can be divided into three stages：early stage, penetrating stage and steady stage. Besides, the bottom crack has little influence on the barrier’s anti-seepage performance, but it is greatly affected by upper or fully penetrated crack. The breakthrough time will be significantly shortened with crack depth increasing until the crack is thoroughly penetrated;and it is better to keep the crack depth under 0.1 time of the barrier’s thickness to ensure its anti-seepage performance. What’s more, with the increase of crack width and permeability coefficient, the water breakthrough time will be rapidly shortened and the steady leakage will increase respectively; and they tend to be stable when they are reaching a certain value. It also shows that the barrier’s anti-seepage performance would significantly deteriorate as soon as the crack is fully penetrated;and the steady leakage will increase linearly with the increase of crack width and permeability coefficient.

关 键 词：垃圾填埋体 压实黏土层 裂隙 优势渗流 水分击穿时间 

分 类 号：TU43[建筑科学—岩土工程]