Abstract: 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 from 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.

Key words: permeability, consolidation, structural characteristics, decomposition degree