深圳福永填埋固化污泥土的工程性质研究

Geotechnical engineering properties of the solidified sludge soil landfilled in Fuyong Shenzhen,China

深圳福永污泥填埋场位于深圳国际机场拟建T4航站楼扩建区中部,填埋场内堆积了大量的固化污泥土,是机场地基处理遇到的难题。为了查清固化污泥土的岩土工程性质,对填埋污泥进行了物质成分分析、微观结构观察、室内外力学试验等。结果表明:固化污泥土中含片状的粘土矿物颗粒、未定型的水化硅酸钙(CSH)、针状的钙矾石以及结构松散的有机絮凝体;土颗粒间孔隙多,孔隙较大(1~6μm),存在大量的微孔隙;固化污泥土具有低密度、低土粒密度、高含水率、高孔隙比、高液塑限等特点;土体十字板抗剪强度值为13.8~23.7 kPa,强度随固结应力的增加而大幅增加;地基承载力特征值为78.9 kPa,变形模量为4.1 MPa,重塑后压缩系数a_(1-2)为3.073 MPa^(-1)。

The Fuyong sludge landfill site is located in the middle of the extension area of Shenzen Inter- national Airport, where it is going to build the T4 terminal. There is a great amount of solidified sludge soil landfilled in this site, which is a difficult problem for airport foundation improvement. In order to find out the geotechnical engineering properties of the solidified sludge soil, experiments including component analysis, microstructure observation, laboratory soil tests and in-situ tests were performed in this study. The results showed that the solidified sludge soil contained flake clay mineral particles, unshaped hydrat- ed calcium silicate （CSH）, needle like ettringite and loose structure organic matters; there were a lot of voids between the soil particals including macrovoid （1 - 6 μm） and microvoid; the solidified sludge soil had characters of low density, low soil particle density, high water content, high void ratio, high liquid limit and high plastic limit; the vane shear strength of the soil was 13.8 - 23.7 kPa and its strength increased greatly with the increase of the consolidation stress ; the characteristic value of foundation bearing capacity was 78. 9 kPa and the deformation modulus was 4. 1 MPa, but the compression coefficient of the remolded soil was 3.073 MPa- 1.