Experimental study on microstructure and mechanical properties of seabed soft soil from South China Sea

Experimental researches on undisturbed soil samples are of great significance for the oil and gas exploitation in South China Sea. The physical and chemical properties of seabed soil in the slope area of South China Sea are studied by using the physical and X-ray diffraction tests. The consolidation and shearing properties are studied by means of the one-dimensional oedometer and conventional triaxial compressive tests. The microstructure is observed by the scanning electron microscope. The results show that the silts are the main compositions, and the soil is of high liquid limit, high void ratio and high saturation. Besides, the soil has large activities, with illite as the primary clay mineral. The soil is under-consolidated and shows traces of structural performance in consolidation tests and strain-hardening behavior in direct shear and conventional compressive triaxial tests. The soil is of flocculated microstructure which has a loose skeleton and weakly ordered grains.