Lower-bound shakedown solutions for transportation infrastructures subjected to moving harmonic loads: A focus on saturated subgrade support

Abstract

As a valuable tool, the shakedown analysis technique can be used to evaluate the long-term resilience of transportation infrastructures subjected to dynamic vehicular loads. In this paper, we introduce a 3-D analytical model that faithfully replicates the geometric complexities inherent in real-world transportation systems. Rather than utilizing the total stress field, modifications to the existing shakedown limit determination methods are executed by focusing on the effective stress field within saturated subsoil. This refined methodology is specifically designed for multi-layered transportation infrastructures like road pavements and rail tracks built over saturated subgrade soils. Upon validation of both the analytical model and the enhanced method for calculating shakedown limits, a systematic investigation into the role of various parameters is conducted. These include the strength ratio, embankment height, and dynamic loading characteristics such as speed and frequency. Subsequent numerical analyses reveal that both the strength ratio and embankment height markedly influence shakedown limits within defined boundaries. Additionally, a comprehensive consideration of load speed and frequency is imperative for an accurate shakedown behavior assessment of the infrastructure in question. The findings validate that the proposed approach offers a more rigorous framework for the optimized design and safety evaluation of transportation systems comprising saturated soil layers.