纤维加筋市政污泥剪切强度试验研究

Experimental Investigation on Shear Strength of Fiber Reinforced Municipal Sludge

随着社会经济的快速发展,市政污泥产量逐年攀升,其安全处置对改善城市生态环境和经济可持续发展具有重要意义。污泥由于含水率高,颗粒细小,粘滞性强,且富含有机质,因而存在机械脱水效率低和抗剪强度低等问题,填埋时容易造成填埋场堆体发生侧滑、失稳等事故。纤维加筋是近些年发展起来的一种土质改良技术,为了研究该技术对污泥剪切强度特性的影响,在不同固结压力下(50,100,200和400 k Pa)对纤维加筋污泥进行了一系列剪切试验,分析了纤维掺量(0,0.05%,0.1%,0.2%,0.4%和0.8%)对固结后污泥含水率、干密度及剪切强度的影响。结果表明:在不同固结压力下,污泥排水固结后的含水率均随着纤维掺量的增加呈先减少后增加的趋势,而干密度则是先增加后减小,试验确定纤维最优掺量为0.1%;污泥排水固结后的剪切强度则随着纤维掺量的增加而增加,纤维加筋作用对污泥的剪切强度提升效果十分明显,100 k Pa下加筋效果最显著;纤维加筋污泥的黏聚力和内摩擦角随纤维掺量的增加而增加,当纤维掺量超过0.4%后,黏聚力增幅有放缓趋势,而内摩擦角的增幅则有加大趋势;在剪切破坏过程后期,随纤维掺量增加,应变硬化趋势更为显著。

With the high development of society,municipal sludge production increased year by year.It has important significance for improving the urban ecological environment and economic sustainable development to efficiently dispose this kind of municipal sludge.Sludge usually has high moisture content,More importantly,it has a very high fraction of organic and fine particles with the high viscosity,and it is not only low efficient to reduce the total volume through mechanical dehydration but has a low strength of the sludge after dehydration,which is easy to cause the landfill pile skid,instability and other accidents.Fiber-reinforcement is a newly developed soil improvement technology.in order to study the effect of fiber reinforcement on sludge sheer strength properties,a series of shear strength tests were conducted on sludge with different fiber contents(0,0.05,0.1,0.2,0.4 and 0.8%)under different consolidation pressure(50,100,200 and 400 kPa).The effect of fiber addition on the moisture content,dry density and shear strength under different consolidation pressure were analyzed.The results showed that under different consolidation pressure,the water content of the sludge decreased firstly and then increased with the increase of the fiber content after the consolidation,while the dry density change trend is opposite,and the experimental determination of the optimal dosage of fiber content is 0.1%.The shear strength of sludge is increased with the increase of the content of the fiber after consolidation,fiber reinforcement effect on sludge are very effective in the shear strength,and the reinforcement effect is the most significant under the 100 kPa.The strain hardening tendency is more significant with the increase of fiber content in the late shear failure process.