Investigating the Nonlinear Soil Behaviour in Piled Barrier Performance

Abstract In road safety applications involving W-beam guardrails embedded in the subgrade, soil plays a crucial role in the overall performance and crashworthiness of the barriers. Previous studies have often relied on simplistic (elastic-perfectly plastic) soil models, such as Mohr–Coulomb, in numerical simulations, failing to capture the intricate nonlinear soil characteristics. A primary challenge in incorporating advanced soil models is capturing the key factors influencing the soil–pile interaction during vehicle impacts, such as strain softening and strain-rate effect. This research aims to provide a better understanding of input parameters and implementation of the Federal Highway Administration (FHWA) soil model, as one of the commonly used advanced constitutive models for crash simulations. For this purpose, we conduct a single pile under pendulum impact and full-scale guardrail (supported by group piles) crash simulations. The W-beam guardrail simulations are validated by real crash test data from the Midwest Roadside Safety Facility. The parametric analyses investigate the effects of soil parameters related to strain softening and strain-rate effect on the overall crashworthiness of the barrier system, an area that has not been previously explored. Among these parameters, the residual friction angle and void formation energy are found to be the most critical parameters, showing a direct influence on vehicle redirection and crashworthiness outcome of the barrier systems.