Coastal reclamation areas typically have soft soil foundations with thick layers of soft soil and a common issue of soil under-consolidation. This leads to problems such as insufficient bearing capacity, prolonged consolidation periods, and significant settlement. To address the low bearing capacity of under-consolidated soft soil foundations, leveraging the Zhuhai Nawan Avenue suspended pile foundation project, a composite foundation model was established using the Flac3D finite difference numerical calculation software. The computed results were compared with short-term monitoring data to validate the accuracy of the model. Extensive research was conducted on the settlement deformation characteristics, pore water pressure dissipation characteristics, and the growth of effective stress in deep under-consolidated soft soil suspended pile composite foundations. The research findings indicate that the model's computed results closely align with the monitoring data, demonstrating that the numerical model accurately reflects the consolidation and settlement characteristics of saturated soft soil composite foundations. This provides a theoretical reference for road construction on deep under-consolidated soft soil foundations.