填埋固化污泥土的压缩过程及微结构变化

中山大学地球科学与地质工程学院,广东广州 510275

岩土工程; 填埋固化污泥土; 压缩试验; 分别加载; 微结构观察; 亚稳定状态

Compression process of the landfilled solidified sludge soil and its microstructure change
Lin Shujiong, Ran Mengjiao, Chen Jianshang, and Zhang Chengbo

Lin Shujiong, Ran Mengjiao, Chen Jianshang, and Zhang ChengboSchool of Earth Science and Geological Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong Province, P.R.China

geotechnical engineering; landfilled solidified sludge soil; compression test; separate loading; microstructure observation; metastable stage

DOI: 10.3724/SP.J.1249.2017.02147

备注

为探讨填埋场中固化污泥土作为地基土的压缩变形特性,通过多组试样分别加载的侧限压缩试验及扫描电镜观察,对固化污泥土在不同应力作用下的变形规律及微结构变化进行研究.压缩试验显示,重塑固化污泥土孔隙比高、压缩性高,在100~200 kPa应力段压缩量较小,存在亚稳定状态,土中含水量随应力的增大呈指数衰减形式下降.成分解析显示:固化污泥土成分复杂,主要为叠片状的黏土矿物土畴,同时还含有矿物碎屑、水化硅酸钙、单硫型水化硫铝酸钙、虫卵、生物碎屑以及各种有机絮凝质等.微结构变化观察显示:应力较小时,颗粒间存在较大的架空状孔隙,是土体压缩性高的主要原因,受水泥固化影响,土体中存在部分强度较高的大孔隙,使土体表现为一种亚稳定状态; 当应力达到400 kPa时,亚稳定状态破坏,颗粒破碎变形严重,呈紧密的镶嵌状接触; 应力增至800 kPa后,颗粒内部小孔隙也被压缩,土体密实度提高,孔隙比达1.445.

In order to explore the compression deformation characteristics of the landfilled solidified sludge soil as foundation soil, confined compression test by separate loading method and scanning electron microscope observation is carried to study the deformation rule and microstructure changes of the soil under different stresses. Compression tests show that, the remold solidified sludge soil has the characteristics of high porosity and compressibility. It has a metastable stage between 100 to 200 kPa, and the compression amount is small. The water content decreases exponentially during compression. Component analysis shows that, the composition of the solidified sludge soil is quite complex, including sheet aggregated clay domain, mineral fragment, hydrated calcium silicate, single sulfur type calcium aluminate, insect eggs, bio detritus, and other organic matters. Microstructure observation shows that, in the low level stress stage, there are a lot of large overhead voids between elements, which is the reason for the high compressibility of the soil. Due to the effect by the cement solidification, the soil has some large voids with highly strength which leads to the metastable stage. When the compress stress comes to 400 kPa, the metastable stage is broken and the particles are damaged and deformed seriously with the contact becoming mosaic. Further increasing the stress to 800 kPa, the micro voids inside the particles are also compressed, and the density of the soil increases, the void reaches 1.445.

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