Abstract: In this paper, both the macroscopic and microscopic mechanical properties of solidified dredged soil were experimentally studied. First, the influence of curing agent dosage and curing age on shear strength and compressive deformation behaviors were analyzed through direct shear test and 1-D compression test. The solidified dredged soil samples were prepared by adding self-made curing agent and commercial curing agent WK-G1 into the sandy soil and clay collected from a large hydraulic fill field in Shanghai coastal area. In addition, the variation of the microstructure of soil samples during solidification was analyzed via scanning electron microscopy. Based on the fractal theory, the fractal dimensions related to particle and void sizes, particle and void distributions, and particle surface fluctuation were extracted using image processing software Image-Pro Plus and self-coded MatLab program. The relationship between microstructure parameters and macro-mechanical property indices was quantitatively explored. Results suggest that for both sandy soil and clay, the compressive modulus and shear strength increased linearly as curing agent dosage and curing age increased; while in microscopic sense, the growth in compressive modulus and shear strength is closely related with the mean area and mean diameter of particle.

Key words: solidified dredged soils, shear strength, compression deformation, microstructure, fractal dimension