Abstract
The recent technological developments made on the light dynamic penetration test Panda 3 R provide a dynamic load–penetration curve σ p − s p for each impact. This curve is influenced by the mechanical and physical properties of the investigated granular media. In order to analyze and exploit the load-penetration curve, a numerical model of penetration test using 3D Discrete Element Method is proposed for reproducing tests in dynamic conditions in granular media. All parameters of impact used in this model have at first been calibrated by respecting mechanical and geometrical properties of the hammer and the rod. There is a good agreement between experimental results and the ones obtained from simulations in 2D or 3D. After creating a sample, we will simulate the Panda 3 R. It is possible to measure directly the dynamic load–penetration curve occurring at the tip for each impact. Using the force and acceleration measured in the top part of the rod, it is possible to separate the incident and reflected waves and then calculate the tip's load-penetration curve. The load–penetration curve obtained is qualitatively similar with that obtained by experimental tests. In addition, the frequency analysis of the measured signals present also a good compliance with that measured in reality when the tip resistance is qualitatively similar.
Highlights
The light dynamic penetrometer with variable energy Panda is widely used to determine the mechanical properties of soils
We are able to rebuild the dynamic load–penetration curve σp − sp from these measurements by using the theory of decoupling the waves propagating in the rod [3]
Some simulation results will be presented in section for validating the signal processing proposed for the Panda 3 R and exploit the signals obtained in the frequency domain
Summary
The light dynamic penetrometer with variable energy Panda is widely used to determine the mechanical properties of soils In the beginning, this device was able to measure only the tip resistance (qd) for each impact by using the Dutch formula with the kinetic energy measured by the strain gauges placed in the head of the apparatus [1]. We are able to rebuild the dynamic load–penetration curve σp − sp from these measurements by using the theory of decoupling the waves propagating in the rod [3] The exploitation of this curve gives us the tip resistance (qd) and other mechanical parameters of the soil such as the wave velocity, the damping coefficient, the elastic modulus [2]. The values of accelerance (A/F(ω)) obtained by the numerical model and by experimental tests of Panda 3 R with similar amplitude of tip resistance (qd ≈ 2MPa) are compared
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