The excavation of hard clay has long been a challenging issue in the dredging industry.To address the problem of low dredging efficiency of hard clay in Lianyungang area,this paper employs discrete element-based fluid-solid coupling numerical simulation to study the cutting characteristics of clay grab heads,examining the dredging process for clays with different cohesion levels.The results show that the conventional high-pressure water jets are effective for dredging soft clay,but when dredging hard clay,high-pressure water cannot penetrate the soil,leading to a series of issues such as high cutting resistance and drag head blockage.Therefore,when excavating hard clay,it is necessary to increase the high-pressure water jet pressure to increase dredging efficiency.