垃圾填埋场中水平导排盲沟渗流模型及间距设计

水平导排盲沟是垃圾填埋场一种重要的堆体内渗沥液导排设施,其水平间距对导排能力和水位控制效果有直接影响。通过建立水平导排盲沟渗流模型,得到了盲沟上水位浸润线的解析解,提出了对应于稳定控制警戒水位要求的水平导排盲沟间距设计方法,并与数值计算结果进行比较。进一步揭示了入流量、垃圾饱和渗透系数、盲沟尺寸、盲沟等效渗透系数和盲沟水平间距对盲沟水位控制能力的影响规律,研究结果表明:当盲沟等效渗透系数小于10~(-4)cm/s时,堆体最大水头及盲沟上水头均明显上升;控制入流量与垃圾饱和渗透系数比值小于0.05时,有利于实现堆体水位控制。基于上述分析,提出了无量纲化的盲沟水平间距设计用图。最后,通过算例分析,验证了文章提出的水平导排盲沟间距设计方法。

Seepage model and spacing design of horizontal trench in landfills

The horizontal trench is a major leachate drainage facility in municipal solid waste (MSW) landfills, of which the spacing design affects drainage and water level greatly. Based on a new seepage model for horizontal trench, the analytical solution of saturation line and the relationship between design spacing of horizontal trench and warning water level can be deduced. The results of numerical calculation agree well with the analytical solutions. It is further revealed that how the inflow, saturated hydraulic conductivity of MSW, size and spacing and equivalent hydraulic conductivity of the horizontal trench influence the capacity of water level control. The results show that the maximum head of waste body and the head at horizontal trench significantly increase when the hydraulic conductivity of horizontal trench drops below 1×10^-4cm/s; and it is in favor of the control of water level when the ratio of the inflow to the saturated hydraulic conductivity of MSW is less than 5×10^-2. A dimensionless figure of spacing design of horizontal trench is proposed, and is verified by a typical case analysis.