基于GDS固结仪的吹填淤泥非线性渗透性及参数测定

 吹填淤泥具有高含水量、高压缩性、低渗透性等特性，因形成条件与应力历史等不同，表现出与一般软黏土不同的渗透特性，很难利用常规渗透试验仪测定渗透系数。GDS固结仪可克服现有渗透试验仪的缺陷，在吹填淤泥非线性渗透特性研究及参数测定方面具有很大的优势。采用GDS固结仪对深圳前湾吹填淤泥进行固结渗透试验，对软黏土常见的4种渗透系数与孔隙比之间的非线性关系进行回归拟合，获得相应的拟合参数。结果表明：(1) 在6～400 kPa的固结压力下，吹填淤泥的渗透系数随固结压力的增加呈非线性变化，降低1～2个数量级；(2) 4种渗透系数与孔隙比之间的非线性渗透关系对于深圳前湾吹填淤泥都是适合的，其中渗透系数与孔隙比之间的幂函数关系，拟合程度最好，形式简单，成为吹填淤泥等超软土大变形与非线性固结性状数值分析首选的非线性渗透关系。

NONLINEAR PERMEABILITY AND PARAMETER DETERMINATION FOR DREDGED FILL BASED ON GDS CONSOLIDATION APPARATUS

Dredged fill behaves some characteristics of high water content，high compressibility and low permeability，due to the difference of formation conditions and stress history. Dredged fill behaves different permeability characteristics from natural soft clays，and it is very difficult to determine its permeability coefficient by conventional permeability test apparatus. The disadvantage of existing permeability test apparatus is overcome by GDS consolidation test apparatus，which has some great advantages for the study of nonlinear permeability characteristics and determining permeability parameter of dredged fill. Consolidation and permeability tests are performed on dredged fill in the Qianwan area of Shenzhen city by GDS consolidation test apparatus. Regression fitting analysis of four common nonlinear function relationships of permeability coefficient-void ratio for soft clays are performed；and some fitting parameters are also obtained. The obtained results indicate that：(1) After a certain consolidation pressure between 6 and 400 kPa，with the increase in consolidation pressure，a nonlinear variation in permeability coefficient of dredged fill is shown，the reduction of which is 1–2 orders of magnitude. (2) Four common nonlinear function relationships of permeability coefficient-void ratio for soft clays are conformable with dredged fill in the Qianwan area of Shenzhen city. Because of the characteristics by a simple form and best fitting，the power function relationship of permeability coefficient-void ratio is considered as a preferred nonlinear permeability relationship in the numerical analysis of large-strain and nonlinear consolidation behaviors of ultra-soft soil such as dredged fill.