Abstract: The construction of the embankment-road widening project experiences challenges, such as differential settlement control. To handle the difficulties, the computational research was conducted to examine the waterfront embankment-road combination project in Jiangbei District, Nanjing. Based on the geological and engineering features, the research was carried out to investigate the three working conditions, known as the natural pile load, step excavation combined with geogrid treatment, and deep cement mixing (DCM) pile treatment. According to the quantitative results, a combination of cement-soil mixing pilecone and probe grouting and geogrid treatment, as well as the step excavation treatment, was used at the stage of the combination of old and new embankments based on data analysis so that the differential settlement could be controlled. The reasonableness of the numerical model was verified by carrying out field monitoring work at the typical section and analyzing the settlement, pore water pressure, and horizontal displacement indexes. Additionally, the actual differential settlement control effect of this design scheme in the embankment-road combination project was evaluated. The results show that the remaining settlement after work in the middle and right shoulders under this design scheme is 16 and 20 mm, respectively, and the differential settlement of the two is below 4 mm. The research indicates that this technique is effective for the coordinated deformation control of the old and new embankments in the project. The approach can guide further treatments of soft soil roadbeds in subsequent riverbank road combination projects.