Effect of NaCl solution on primary physical-mechanical behaviors of deep-sea sediments

The environment of the salt solution in deep sea can be greatly disturbed by the ocean currents and oil-gas exploitation. Therefore, it is necessary to explore the effects of saline solution on the physical-mechanical behaviors of the deep-sea sediments. The effects of sodium chloride solution on the microscopic fabrics of the deep-sea sediments from the South China Sea are firstly explored using the scanning electron microscope. Subsequently, different methods are used to measure the basic physical properties, rheological and deformation characteristics of the deep-sea sediments under variable concentrations of saline solutions, including free settlement, liquid limit, rheology and consolidation tests. The results show that the flocculated structure is enhanced in the sediments under the effects of saline solutions with the scanning electron microscope. Furthermore, the settling velocity of the sediment particles in the saline sotuion is much larger than that in the deionized water. The free settlement curves can be divided into three characteristic stages. The liquid limit and yield stress of the sediments also increase when the concentration of the saline solution increases. It’s worth noting that the yield stress saturated by the NaCl solution with the concentration 1.0 mol/L is three times larger than that saturated with deionized water. The oedometric moduli of the sediments increase with the increasing concentration of NaCl solution.