城市生活垃圾焚烧渣工程特性试验研究

Experimental study on engineering characteristics of incineration bottom ash of municipal solid waste

焚烧法减量效果显著,已成为生活垃圾的主要处理方法,然而城市生活垃圾焚烧会产生大量底渣,底渣如何处置利用是当前一个重要且亟待解决的难题。以武汉地区底渣为例,借助微观观测技术和室内测试试验,较为全面地分析武汉底渣的物理、化学及工程特性,与不同地区底渣特性进行对比,并进一步探讨武汉底渣在道路工程中作为路基填料、垃圾填埋场中用作防渗层的可行性。结果表明,底渣颗粒形状各异,表面光滑且有细小孔洞,是一种塑性较低、比重较高的级配不良砂性粗粒土;底渣重金属元素浸出浓度均未超过国家相关标准的规定限值;底渣的击实性与中细砂相似,有一定的压缩性,但其固结特性不明显;底渣的渗透系数略大于细砂,经掺和膨润土后可考虑用作垃圾填埋场防渗材料;底渣内摩擦角接近中细砂取值,同时还具有一定的黏聚力;在承载变形能力上,底渣的CBR测定值较高,满足路基工程材料对承载力的要求。

Incineration method has remarkable reduction effect and has become the main treatment method for municipal solid waste.However,incineration would produce a large amount of slag,for reuse of municipal solid waste incineration bottom ash,this paper investigated the bottom ash from a Wuhan incineration plant,and comprehensively analyzed the physical,chemical and engineering characteristics of the bottom ash by experiments and testing.Then the characteristics of bottom ash in different areas were summarized and compared with the present study.Furthermore,the feasibility of using the bottom ash as subgrade material in road engineering was discussed.The results show that,the bottom ash particles are various and randomly arranged,and the surface is smooth and distributed with obvious fine pores.The bottom ash is classified as a poorly graded coarse-grained sandy soil with low plasticity and high specific gravity.The leaching concentration of heavy metals from this bottom ash does not exceed the threshold value specified in the relevant national standards.The compaction characteristics of this bottom ash are similar with those of sand or gravel,it has relatively low compressibility,and its consolidation characteristics are not obvious.The permeability coefficient of the bottom ash is slightly greater than that of fine sand,and it can be considered as a landfill impermeable layer after being mixed with bentonite.The internal friction angle of bottom ash is close to that of gravel and has certain cohesion.In terms of the bearing capacity,the relatively high CBR reveals that the bearing capacity of this bottom ash meets the requirement of subgrade materials in road engineering.