Soil-Embedded Guardrail Post Modeling under Vehicle Impacts
Publication: Geo-Congress 2023
ABSTRACT
Guardrails, consisting of soil-embedded piles tied with a thrie-beam rail, are safety barriers installed along highways to shield errant motorists from roadside hazards and minimize the risk of serious injuries. Soil resistance plays a crucial role in the way that guardrails deflect when impacted by vehicles. Guardrails require special consideration over culverts as the soil fill depth provided over culverts is not generally sufficient to embed standard 1,016-mm (40-in.) deep guardrail posts. Various methods have been developed to enable post attachment to culvert structures. It would be desirable to use more closely spaced posts at a reduced embedment depth rather than introduce new hardware. However, the performance of the guardrails with post embedment depths less than 40 in. has not been evaluated. Thus, a need exists to determine the potential for using reduced post embedment and/or reduced post spacing with the guardrail to span low-fill culverts that satisfy MASH crashworthy criteria under TL-2 and TL-3 impact conditions. In this research, efforts were conducted to investigate the load-deflection behavior of a single post under impact through a series of dynamic, large-scale, component testing (with a surrogate vehicle, namely bogie) and numerical simulation using LS-DYNA. Baseline dynamic tests were performed on a steel W6x16 post embedded in crushed limestone soil with different depths impacted by a bogie vehicle. Additional six bogie tests were conducted on W6x8.5 posts with various depths. Test results were used to develop simplified numerical modeling of the soil-pile/soil-post system when impacted by a vehicle. The validated model would be used to study other impact cases with different vehicle models and post embedment depths compared to associated full-scale crash test data and investigate the accuracy of the proposed soil modeling method to represent soil and post behavior in crash tests.
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Geo-Congress 2023
Pages: 151 - 162
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Published online: Mar 23, 2023
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