Marine nepheloid layer is widely distributed in the oceans and marginal seas. The concentration of suspended particles in the nepheloid layer is significantly higher than that of the adjacent layers. Marine nepheloid layers include the surface nepheloid layer (SNL), intermediate nepheloid layer (INL), and bottom nepheloid layer (BNL). As a transport pathway for the particulate matter in the oceans, nepheloid layer is important to the carbon cycle and the source–sink system at the continental margin. This paper focused on the characteristics of the marine nepheloid layer and the mechanism of internal solitary waves that form INL and BNL, providing a reference for further research on the marine ecological environment dynamic process and source–sink system. BNL is formed by suspended seabed sediments with strong currents near the bottom, but the fate of BNL remains unknown. Marine nepheloid layer significantly affects the transportation of materials within the ocean. The transport of sediments by ISWs dramatically affects the formation of deep seabed sedimentary landform. However, the formation process and the transport contribution of INL and BNL are still unclear. The systematic and long-term research on the marine nepheloid layer in the world oceans is still limited.

The waste mud from slurry shield tunnel construction can easily cause environmental pollution. Thus, the RCSLP curing agent is developed to reutilize the waste mud produced in the Jinan Yellow River tunnel. The strength properties of the soils solidified with cement or RCSLP were tested, and their microstructures were studied by scanning electron microscopy. The results show that for the RCSLP curing agent, an optimum cement content of 15% and an optimum additive content of 12% improved the early compressive strength of the solidified soil. The mechanical properties of the RCSLP solidified soil were improved due to the significantly increased hydration products. The findings of this research could help achieve the utilization of waste mud from slurry shield tunnel construction.

Gassy sediments are an important cause of engineering disasters such as large-area coastal submarine landslides, excessive tilting of marine foundations, and excessive deformation of tunnels. Under different stress paths, the gassy soil exhibits different microstructure changes and mechanical responses. This paper introduces the current research status regarding the mechanical responses, numerical simulation and the in-situ test methods of gassy sediment. In terms of mechanical responses, it summarized the strength and deformation characteristics of gassy soil under different stress paths, tracking the study on constitutive model. The disaster simulation work using constitutive model of gassy sediment is introduced. It also analyzes the advantages and limitations of various methods in the in-situ test. It can provide theoretical support for further study on disaster prevention and geological risk assessment of gassy sediments.

Soil dilatancy and partial drainage have great influence on the consolidation coefficient assessment of silty soils with clay content of less than 30% in the Yellow River Delta using the CPTu. This paper discussed the effect of soil dilatancy and partial drainage on the pore pressure response and dissipation of piezocone test in shallow silty soil of the Yellow River Delta through variable penetration rate tests in a pressure chamber and a series of supplementary soil element tests. The results show that the pore pressure dissipation curve is affected by soil type and degree of consolidation. The soil dilatancy is the key factor affecting consolidation coefficient inversion of shallow silt and silty clays. The initial pore pressure is negative and the pore pressure increases to u_max first, but the u_max value is very small in the Yellow River Delta silt. The inversion method used for shear contractile soil cannot be used to invert the mechanical properties of shallow silty soil directly, and a new consolidation curve normalization method is proposed. This paper provides a reference for the consolidation coefficient inversion of CPTu data in the Yellow River Delta area.