In heavy-duty storage yard projects located in soft soil regions,differential settlement frequently causes instability in yard foundation and rail facilities,while conventional plastic geogrid reinforcement demonstrates limited effectiveness.Focusing on the phase Ⅰ container terminal renovation project in Luojing port area of Shanghai Port,we propose a technique of container yard structure-foundation integrated stiffness enhancement using steel geogrid-reinforced gravel cushion to improve integral rigidity of structure-foundation and reduce differential settlement.We systematically investigate its optimized design through FLAC3D numerical simulations and discuss the influence mechanisms of cushion material properties and steel geogrid layering configuration on differential settlement control.The results show that although increasing the elastic modulus of cushion materials reduces total settlement slightly,its effectiveness in mitigating differential settlement remains constrained.Conversely,additional steel geogrid layers significantly decrease differential settlement,achieving a 31%-45.4% reduction with two-layer installation.However,the improvement rate diminishes with further layer additions.Considering economic viability and project benefit,the solution of combining dual-layer steel geogrids with 80 MPa elastic modulus graded crushed stone is recommended.The solution reduces differential settlement between strip foundations and rail tracks by 15%-29.02%,simultaneously forming a rigid stiffened layer that enhances overall foundation stiffness and suppresses lateral deformation.