In port dock engineering, high-piled wharves represent one of the primary structural forms. Damage to the foundation piles is a common issue, influenced by external loads such as impact forces during vessel berthing, slope deformations, and operational loads. This study focuses on the Jungong Road Wharf in Shanghai, utilizing FLAC 3D version 6.0 to conduct dynamic calculations under ship impact loading. The dynamic responses of the structure were analyzed, and various internal forces were extracted during the impact event. By combining concrete cracking failure criteria and fatigue damage theories, the effects of ship collisions on the cracking damage of high-piled wharf structures under different scenarios were assessed. Additionally, the applicability of modal flexibility in high-piled wharf scenarios was evaluated through finite element simulations. The results indicate that the dynamic amplification factor caused by dynamic loading is approximately 1.5, underscoring the necessity of considering this effect in the design and impact analysis of high-piled wharves. The impact loading significantly influences the bending moments of the piles, with inclined piles showing the greatest sensitivity. When a designed ship model collides with the high-piled wharf structure at a speed of 0.2 m/s, the tensile stress in the inclined piles reaches 87% of the ultimate tensile strength of the reinforcement. The impact loading has a relatively minor effect on the axial forces of the piles, a limited influence on the bending moments of the beams, but a considerable impact on the axial forces of the beams. Berthing by oversized vessels and unexpected incidents can lead to more severe damage to high-piled wharf structures. In the finite element simulations, modal flexibility effectively identified the locations of damage, with greater changes in modal flexibility correlating with increased damage severity.

Dynamic compaction is a widely used method to strengthen the foundation, which can cause significant impacts on surrounding structures, making vibration control measures necessary. This study investigates the effectiveness of isolation trenches in reducing ground vibration caused by dynamic compaction in a typical multi-layered alluvial soil foundation adjacent to the Yangtze River. A combination of field testing and numerical simulation was employed to evaluate the vibration isolation effect of trenches at different depths and locations. The results show that trenches have a significant vibration isolation effect on the side away from the tamping point, but they can have an amplifying effect between the trench and tamping point. The effectiveness of the isolation trenches increases with deeper trenches and distance from the tamping point, but the amplification effect decreases with increasing depth. Therefore, when employing trenches, reinforcement measures must be adopted, and a suitable trench depth should be selected. The closer the isolation trench to the dike, the better the protection will be. The study provides effective guidance for designing isolation trenches in similar dynamic compaction processes, emphasizing the importance of considering spatial attenuation characteristics and selecting appropriate trench depths and locations.

In the marine environment, harbor structures are prone to fatigue damage due to long-term berthing load, accelerating chloride erosion and leading to steel corrosion, thus significantly reducing the durability and service performance of reinforced concrete structures. To investigate the influence of fatigue damage on chloride ion diffusion, this paper simulated the damage degradation process of structures under fatigue load and chloride ion erosion through experiments. The damage caused by fatigue load was defined by ultrasonic method, and the study investigated the effects of different stress levels and loading cycles on chloride ion transport. The chloride ion diffusion concentration under different damage conditions was predicted by numerical simulation. The results indicate that the fatigue load leads to the increase of load level and the increase of chloride ion content at the same depth. The increase of loading times accelerates the penetration rate, which is positively correlated with the chloride ion diffusivity. The chloride ion diffusion coefficient of concrete exhibits an exponential relationship with fatigue damage levels. The numerical simulation results are consistent with the experimental results, validating the feasibility of establishing a correspondence between thermodynamic diffusion and chloride ion diffusion parameters using the analogy method. This paper provides reliable support for the performance assessment and maintenance of reinforced concrete structures in marine environments.