纯黏土与砂-黏土混合物渗透特性差异及机理分析
Difference and mechanism analysis on percolation behavior of pure clay and sand-clay mixtures

根据重塑纯黏土和砂-黏土混合物试样的室内固结试验结果,反演了渗透系数,探讨了纯黏土和砂-黏土混合物的渗透特性差异.试验结果表明:常用于评价纯黏土渗透性状的归一化指标e/eL(孔隙比与液限状态孔隙比的比值)能拓展运用于砂-黏土混合物中,但e/eL与渗透系数之间呈现非线性关系,这显著不同于纯黏土的线性关系,其本质原因在于混合物在压缩过程中形成了砂骨架.骨架形成前,纯黏土和砂-黏土混合物的e/eL与渗透系数的2条关系曲线吻合良好,而在骨架形成后,两者的关系曲线存在明显的差异;引入砂-黏土混合物四相体系,从黏土孔隙比和砂孔隙比的角度阐述了砂骨架的形成机制,且对两者渗透性状的差异性进行了详细的机理解释;最后给出了一种可以预测纯黏土和砂-黏土混合物渗透系数的经验公式.
To investigate the difference of percolation behavior between pure clay and sand-clay mixtures, the oedometer consolidation experiments were performed using artificially remolded samples and the permeability was back analyzed. The results show that the normalized index e/eL(the ratio of void ratio to that at liquid limit)commonly used can be extended to the sand-clay mixtures, while the nonlinear relationship between permeability and this index is observed, which is different from a linear relationship is pure clay. This obvious difference is attributed to the formation of the sand skeleton in sand-clay mixtures. Percolation behavior of pure clay and sand-clay mixtures is the same before the formation of the sand skeleton, while the difference occurs after the formation. The four-phase analysis system of clay-sand mixtures is adopted to clarify the formation of the sand skeleton and the difference of percolation behavior between the pure clay and sand-clay mixtures in the view of the sand void ratio and clay void ratio. Finally, an empirical formula to predict the permeability coefficient of pure clay and sand-clay mixtures is proposed