高有机质软土固结特性与机制分析

Analysis of formation mechanism and consolidation characteristics of high organic soft clay

有机质中的纤维素和腐殖质会影响软土的力学性质，有机质含量越高，软土的力学特性就会越差。为研究高有机质软土的固结特性，通过对不同深度高有机质软土的渗透性、固结以及微、细观结构特征进行试验，并利用分解程度试验结果，分析高有机质软土的特殊渗透、固结和结构特征的形成机制。研究结果表明，不同埋深的高有机质软土渗透系数差别较大，且渗透固结速度较快，基本处于粉砂到粉质黏土数量级；0．5～1．8m埋深的土层垂直渗透系数小于水平渗透系数，其余深度垂直渗透系数均大于水平渗透系数；分解程度的研究表明，分解程度直接影响高有机质软土的压缩固结特性，低分解程度的土层更容易发生塑性变形。由埋藏从浅到深，结构由絮凝结构逐渐向叠片结构转化，最后转变为集块结构。结合土体的分解程度分析，得出高有机质软土的分解程度高低直接影响高有机质软土的渗透、固结以及结构特性。

Cellulose organic matter and hummus will affect the mechanical properties of soft soil. The higher of the Organic matter content, the worse of the mechanical properties. To study the consolidation characteristics of high organic soft clay, the formation mechanisms of permeability, consolidation and structural characteristics are analyzed by the test of decomposition degree after the tests of permeability, consolidation, micro-meso structural characteristics at different depths. The results indicate that permeability coefficients have larger difference at different depths; and permeability and consolidation speed are faster. The value of permeability coefficient is during silt to silty clay magnitude; The vertical permeability coefficients are smaller than horizontal permeability coefficients at depths ~om 0.5m to 1.8m. and others are lagger than horizontal coefficients. The decomposition degree studies have shown that decomposition degree will affect the consolidation characteristics directly; and lower decomposition degree will easer lead to plastic deformation. Also the structure changes from flocculated structure to laminatted structure according to different depths, and transforms into massive structure finally. It proved that the characteristics of permeability, consolidation and structure have been direct effected by the degree of decomposition after the decomposition degree is analyzed.