Effect of organic matter content on Atterberg limits and undrained shear strength of river sediment

The Atterberg limits and the undrained shear strength are crucial soil properties in the preloading design of reclamation foundation projects using dredged river sediment. These properties can be significantly affected by the presence of organic matter in the sediment. This study investigates the physical properties and undrained shear strength of river sediment, based on data from a series of fall cone tests performed on river sediment with different organic matter contents, and undrained shear strength data for reconstituted clay collected from the literature. It was found that the liquid limit, plastic limit, and plasticity index increase with an increase in organic matter content. The effect of organic matter on the undrained shear strength of remolded soil at a given water content can be attributed to the effect of organic matter on the liquid and plastic limits. The undrained shear strength is a function of the liquid and plastic limits; it can be normalized by the liquidity index, irrespective of the organic matter content.

Automated summary

The presence of organic matter in river sediment affects important soil properties like liquid limit, plastic limit, and plasticity index, which increase with higher organic matter content. The impact of organic matter on the undrained shear strength of soil is attributed to its effect on liquid and plastic limits. Shear strength can be normalized by the liquidity index regardless of the organic matter content.