填埋场固化污泥工程特性变化研究

深圳机场北污泥填埋场将作为机场扩建场地,其填埋的固化污泥将作为地基使用。对填埋场固化污泥进行了岩土工程特性研究,包括有机质含量、含水率、初始孔隙比、界限含水率、颗粒级配、微观结构、压缩固结特性以及抗剪强度等。结果表明:固化污泥的有机质含量、含水率、孔隙比都随着埋深的增加而减小,其中填埋后有机质含量的变化与污泥的降解程度有关,是含水率及孔隙比变化的内在原因;污泥的液、塑限高,液性指数大于1,表观状态却呈现固体状态;固化污泥是多孔隙介质,结构性较差;固化污泥是高压缩性和欠固结土,其固结系数基本与常规淤泥相近,且随固结压力的增加而显著增大,呈现典型的大变形固结特性;固化污泥原状土和重塑土的抗剪强度均随着埋深的增加而增加,其中,随着埋深的增加,原状土的抗剪强度从13.8 kPa增加至23.7 kPa,重塑土的抗剪强度从13.0 kPa增加至14.3 kPa,这与污泥结构强弱密切相关。

Research on Changes of Geotechnical Properties of Solidified Sludge at Landfill

The sludge landfill, located in the north of Shenzhen airport, is in rang of the airport expansion field. The solidified sludge at landfill will be used as the foundation. Geotechnical properties of the solidified sludge were investigated, including organic content, water content, initial void ratio, limit content, particle-size distribution, microstructure compression consolidation properties and shear strength. The results showed that the organic content of solidified sludge decreased with the increase of depth, related to the degree of degradation. The change rules of water content and initial void ratio were the same as the organic content. The change of organic content after landfilled was the internal reason for the changes of water content and initial void ratio. The solidified sludge had high limit content, and though the values of liquidity index are greater than 1, the apparent state of sludge performances solid state. Solidified sludge was porous medium and its structural was poor. Solidified sludge was high compressive and under consolidated soil. The consolidation coefficients of solidified sludge were close to conventional muddy soil and showed a decreasing trend with the increase of consolidation pressure, presenting a typical large deformation consolidation properties. With the increase of depth, the shear strengths of the undisturbed solidified sludge increased from 13.8kPa to 23.7kPa, and the shear strengths of remoulded solidified sludge increased from 13.0kPa to 14.3kPa. The intensity of sludge structure played a decisive role in the changes of shear strength.