Robust Geotechnical Design of Transition Zone Material Parameters Based on Fuzzy Set Theory

A safe and economical design of high-speed railway subgrade-bridge transition zone nowadays relies heavily on the accuracy of the geotechnical parameter measurements, while inherent variability, testing error and transformation error often stand in the way. This paper presents a fuzzy set-based robust geotechnical design (RGD) methodology for the transition zone, freeing the design from the requirement of precise geotechnical parameters. Based on the theory of vehicle-track coupling dynamics, a plane stress finite-infinite element model of the transition zone is proposed to investigate the influence of 3 simultaneously varied subgrade material parameters on the system dynamic response. Using the vertex method, the subgrade system’s robustness is evaluated by the signal-to-noise ratio. The results indicate that the influence of the dynamic elastic modulus of the graded broken stone on the robustness of the vehicle system is considerably larger than that of the dynamic elastic modulus of the subgrade bed surface layer. The system is more robust when the dynamic elastic modulus of the graded broken stone is between 625 Mpa and 750 Mpa.