Numerical simulations of vehicle impact on security barriers considering soil-barrier interaction

What can be the contribution of numerical simulations?

Vehicle Security Barriers (VSBs) are frequently utilised in urban settings to defend against vehicular terrorist attacks. They come in various forms, including bollards, street furniture and landscape features. The effectiveness of such barriers is usually assessed through a vehicle impact test, in accordance with test standards. Substantial costs of impact tests restrict the amount of impact scenarios that can be analysed. Numerical simulation methods can virtually test barriers. Practical configurations, such as different impact speeds, angles, and site conditions can be assessed.

Why focussing on soil and its interaction with the barrier and its foundation?

As stated in several VSB-related impact test standards, such as the new ISO 22343, soil conditions can significantly influence the performance of VSBs. However, test standards often lack comprehensive guidance on how to deal with soil conditions. The report investigates this relationship and underscores the importance of considering soil conditions during VSB design. Furthermore, it highlights the need for consistent soil assessments.

The missing piece of a comprehensive methodology for numeric modelling of the soil domain

While numerical vehicle models of vehicle categories are available and can be utilized, a comprehensive methodology for numerically modelling of the surrounding soil domain of a VSB was not available. To this aim, the report investigates the critical role of soil domain dimensions, the influence of the finite element size in the meshed soil domain, and soil modelling strategies. Sensitivity studies highlight the role and influence of soil material properties on the VSB response upon impact.

The report demonstrates that numerical simulations can be a useful tool to investigate the influence of various soil types. The findings emphasize the need for a proper consideration and a soil-focused approach during testing phases and subsequent installation of vehicle security barriers.

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What could be next steps?

We do not stop here. There are several subjects that we consider for future research. Notably, in this report, a homogeneous soil domain with a specific soil type was investigated. Among others, future research may consider combinations of surface and subbase constructions (stratified soil conditions), different environmental conditions of the soil (e.g., wet, dry, frozen soil) and the influence of existing underground infrastructure (cabling, piping, underground concrete tunnels, etc.).