Experimental and numerical analysis of soil structure interaction during high-speed load

Despite being at the two edge of soil dynamics, blast and earthquake engineering find a common ground by looking for solution able to develop resilient structures and infrastructures. In this field, the soil structure interaction (SSI) and the development of constitutive models, especially for geomaterials, play a significant role. Moreover, experimental data are extremely precious, and their use could be of great interest for anyone interested in developing resilient solution. In addition to this, the assessment of the prediction capabilities of numerical tools is a core theme for both researchers and engineers involved in day-to-day practice. The authors show in the paper the results of a ground shock test and its subsequent numerical analysis. A small charge was detonated in a shallow partially compacted ground (the derivation of soil material parameters is here only briefly addressed since it is not the focus of the study, however a relevant paper is currently under submission). Pressures and arrival times have been measured through the soil material by means of pressure sensors and steel plates equipped with strain gauges. A reinforced concrete box was also put in place facing the charge and its response has been measured in terms of contact pressure, displacement, and acceleration. A 3D numerical model was then implemented in the commercial hydrocode Autodyn. The soil was model by means of the Euler formulation whereas for the RC box a lagrangian approach was adopted. A fully coupled contact formulation was then established to catch the soil structure interaction. The results of the explicit dynamic analysis of the shock test gave encouraging results in terms of catching the maximum response in terms of peak soil pressures, acceleration response spectra, and maximum displacement. On the other hand, the analysis proved to be quite demanding from the computational point of view. Despite the challenges involved, results are encouraging, and they establish a ground for future research and for the development of proper tools and methodologies.