The deep-sea sediment is exploited in the Pacific C-C district by our research group. Its physico-mechanical properties are studied by analysis of laser particle size
test of liquid and plastic limit
tests of nitrogen adsorption
consolidation and direct shear
and its mineral compositions and microstructures are analyzed by X-ray diffraction(XRD) and scanning electronic microscope(SEM) methods
respectively. Test results show that the deep-sea sediment is clay soil with predominant silt. It has properties of high liquid limit
high plasticity
high specific surface area
high consolidation coefficient
low compressive modulus and low shear strength
which easily results in slip and subsidence of the deep-sea mining machine. It is mainly composed of montmorillonite
quartz
feldspar
mica
chlorite and serpentine
with sheet-linked microstructure of silt and microbial debris filling with honeycomb flocculation microstructure of clay mineral together. The simulative soil substituting for the deep-sea sediment should be prepared based on the mineral composition
particle size
water content
specific surface area and shear strength as well as liquid limit
plastic limit and microstructure of the deep-sea sediment. The research results can provide an important basis for walking-characteristic study and optimization design of the deep-sea mining machine.