填埋场排水层结构对其渗透性能的影响

垃圾填埋场存在着因渗滤液收集和排水系统渗透性能减弱而失效的问题,威胁着填埋场的安全稳定及其周边地质环境。因此,研究填埋场排水层结构及其渗透性演变规律对垃圾填埋场的正常运营及其对周边环境的影响评价具有重要现实意义。以相似理论为基础,采用现场垃圾渗滤液作为渗流流体,对比分析了2种结构排水层、3个渗流段的排水孔隙度和渗透性的演变规律。研究结果表明:渗滤液在单粒组结构排水层渗流时,第3渗流段渗透性的变化滞后于第2渗流段及第1渗流段;砂砾粒径较渗流深度对排水孔隙度的影响作用更大;砂砾粒径越大,排水层淤堵的发生时间越晚;在排水层中间段设置粒径较大的砂砾层,可以减缓排水层渗透性的降低速率。

EFFECT OF LANDFILL DRAINAGE LAYER STRUCTURE ON ITS PERMEABILITY

The problem of the failure due to leachate collection and the shortage of drainage system permeability was widespread in landfill sites,which threatened the safety and stability of landfill and its surrounding geological environment.Therefore,the research of landfill drainage layer structure and its permeability evolution law had important practical significance to the normal operation of the landfill and its impact assessment of surrounding environment.Based on the similarity theory,the evolution law of the drainage porosity and the permeability for two drainage layers and three seepage sections were analyzed,which used the landfill leachate as the seepage fluid.The results showed that:During the seepage of single grain drainage structure,the third seepage stage lagged behind the the first two stages;gravel size had a greater influence on drainage porosity compared with seepage depth;the larger particle size was,the later the formation of the drainage layer blocked;it set gravel layer which had larger size in the middle period of drainage layer,which could retard the reduce speed of drainage layer permeability.