Abstract: The submarine cone penetration test (CPT) is a widely used insitu test method on the seabed. Based on the discrete element method, a discrete element model is used to simulate and analyze the in-situ measurement process of the probe penetrating the seabed soil. The underwater saturation state of the seabed soil is simulated by adding soil particle buoyancy and one-way fluid-solid coupling respectively, as well as the surface penetration model of the dry sand and two saturated soils are established. For the deep penetration, a 200 m soil depth penetration model using one-way fluid-solid coupling method is established. The numerical simulation results show that the soil particle response of the probe penetrating the saturated soil is significantly different from that of the unsaturated soil in terms of the force-related results such as tip resistance and the particle stress. The one-way fluid-solid coupling method can better simulate the underwater saturation state of the soil than adding soil particle buoyancy. In terms of tip resistance, only considering the buoyancy of soil particles will produce a difference of 9 %. In the surface penetration and deep penetration of the probe rod, the large stress of the soil particles is concentrated at the cone tip of the probe rod, and the related soil disturbance such as the displacement and rotation of the soil particles mainly occurs within a diameter range of the probe rod from the cone shaft.

Key words: Discrete Element Method, Numerical Simulation, One-Way Fluid-Solid Coupling, Saturated Soil, In-Situ Test