Damage mechanisms of port structures such as breakwater and seawall have been studied in the past, and there are mainly three causes; I. horizontal force due to the water level difference between the front and rear breakwater, II. soil scour and erosion behind the seawall during overflow and III. piping destruction associated with the decline of the bearing capacity by seepage flow. In this study, a particle simulation tool based on the SPH has been developed to solve the different soil damage mechanisms; soil sour and seepage flow problem. These simulations should treat the Fluid-Soil and Fluid-Seepage flow interactions, and the particle simulation tool has been modified and improved to solve each interaction problem. For the Fluid-Soil interactions in the soil scour problem, soil is modeled by a Bingham flow model which is one of the non-Newtonian fluids, and the Mohr-Coulomb criterion is applied in the plastic yield judgment. On the other hand, in the seepage flow analysis, surface flow and seepage flow are described by the same government equation "Darcy-Brinkman equation", and simultaneous analysis is carried out. These different simulations have been implemented by modifying the standard SPH method.