基于渗透特性的MSW颗粒组成和结构分析

在南方某填埋场埋深5~30m范围内取6组重约5kg的试样，对其进行筛分与分拣，研究垃圾颗粒组成随埋深的变化规律，同时对不同荷载作用下的垃圾试样进行染色切片，对比分析上覆压力对垃圾内部结构的影响.结果表明：对于不同埋深的城市固体废弃物，细颗粒（0D，即粒径<2cm）所占比例最大，几乎均超过50%，粗粒中2D颗粒所占比例最高，而塑料在2D颗粒中占比最大；随着荷载的增大，细粒含量增加，大孔隙和优先流通道减小.上覆压力主要通过减少垃圾内部孔隙通道，进而减小渗透系数；2D颗粒在荷载的作用下能定向排列，使渗流路径发生曲折，进而导致渗流各向异性.2D颗粒的定向排列是垃圾渗流各向异性产生的关键因素，其中塑料又是其最重要的因素.

Analysis of particle composition and stucture of MSW based on permeability

In a southern landfill, 6samples weighing about 5kg were collected at the depth of 5~30m. The samples were sieved and sorted to study the variation of the particle composition with the depth. Meanwhile, the samples under different loads were stained and sectioned to analyze the influence of overburden pressure on the internal structure of MSW. The results showed that the fine particles (0D, i.e., particle size <2cm) were the most content in the MSW samples and its proportion exceeded 50%. The proportion of 2D particles was the highest in coarse particles, and the plastic was the most content in the 2D particles. As the load increased, the content of fine particles increased, while the large pores and preferential flow channels decreased. The overburden pressure mainly reduced the internal pore space of MSW, and then decreased its hydraulic conductivity. 2D particles could be directionally arranged under loading, which led to the tortuosity of seepage path and the anisotropy of hydraulic conductivity. The directional arrangement of 2D particles was the key factor resulting in the seepage anisotropy of MSW, and the plastic was the most important factor.