Interaction between safety barrier and soil

The dynamic soil-structure interaction which takes place when the guardrail posts of a safety barrier transfers the kinetic energy coming from an impact is rather complex and relatively little know phenomenon. The experimentation described here has the purpose, therefore, of understanding the fundamental mechanisms involved in this dynamic event. Three impact tests were carried out on a real scale, using a pendulum having a known mass on as many guardrail posts fitted out with strain gages, fixed into a soil having known features, since it had been reconstructed. Knowing the kinematic and dynamic features of the impact, we were able to describe the interaction of the structure with the soil right up to breaking of the latter, basing ourselves on energy balances and on the stress state in the guardrail post. Depending on the maximum energies which can be dissipated into the soil, it is also possible to assess the suitability of installing very resistant barriers on the edge of the road embankments and above all to settle a new simplified design method for soil posts interaction.