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Comportement des sables sous sollicitation d’impact à faible vitesse : application au dimensionnement de couches de sol protégeant les structures des impacts rocheux

Abstract : An extensive experimental parametric study has been carried out to characterize how impact loads of low velocity (lower than 100 km/h) are transmitted to a structure through a protective sand layer. Different rock fall conditions have been considered, corresponding to actual conditions in current practice. The experimental program consisted of 43 full scale impact tests on a sand layer protecting a concrete foundation mat, combining three sand layer thicknesses (1, 1.5 and 2 m), impacting blocs of equivalent diameters in the range of 0.42 to 1.79 m and five free falling heights, up to 33 m. Based on the analysis of pressure cells measurements for the different rock fall conditions, the pressure induced at the interface between the protective sol layer and the structure by an impact was expressed in terms of impact conditions, defined by layer thickness (D), size of the impacting bloc (B) and height of free fall (H). Procedures to derive the model parameters from the tests are explained in detail. A numerical model was developed to simulate an impact on a structure protected by a soil layer based on a deformation analysis approach. The Finite Element code ABAQUS was used. The bloc, the soil and the structure were considered as different bodies, having contact conditions between them. The stress‐strain relationship in the soil was assumed to be elastoplastic. Friction angle and dilation angles were derived from laboratory tests on the sand. The elastic modulus was assumed constant, equal to usual values for compacted sands. An approach is proposed for the design of soil layers to protect structures from impacting loads due to rock falls.
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Submitted on : Thursday, November 15, 2018 - 1:03:05 PM
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Tarik Oussalah. Comportement des sables sous sollicitation d’impact à faible vitesse : application au dimensionnement de couches de sol protégeant les structures des impacts rocheux. Matériaux. Université de Lyon, 2018. Français. ⟨NNT : 2018LYSET004⟩. ⟨tel-01923593⟩

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