Numerical Study on the Asphalt Concrete Structure for Blast and Impact Load Using the Karagozian and Case Concrete Model  
[PERSON]  
1 The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing 100124, China; [EMAIL_ADDRESS] (J.W. ); [EMAIL_ADDRESS] (X.D. )1 The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing 100124, China; cvewujun@sues. stress was significantly dependent on the strain rate. [PERSON] et al. [4] carried out tests on AC under uniaxial and triaxial compression with the strain rate changing from \(10^{-4}\) s\({}^{-1}\) to 0.07 s\({}^{-1}\). The results showed that with the increase of the applied strain rates, the yield stress and failure stress increased, and the strain rate dependency was clearly showing up at the higher strains. It was also found that the viscous behaviour of AC decreased with the increase of the strain rate. However, when the pavement structure is subjected to the impact loading from further heavy traffic loading or aircraft loading, the corresponding strain rate exceeds \(10^{-1}\) s\({}^{-1}\), especially for heavy aircraft loading, the related strain rate reaches around 100 s\({}^{-1}\). Based on previous research [5; 6], the compressive strength of AC material can be enhanced with the increase of strain rate, and AC material exhibits high plastic behaviour at the high strain rate. However, it is very expensive to conduct field test to investigate the actual behaviour of AC under severe dynamic loading, the numerical simulation is an effective alternative solution. There are many factors that influence the reliability of numerical simulation. Among these factors, the material model plays a key role because it should reproduce the essential physical mechanisms of the material under various loading conditions. [PERSON] et al. [3] and [PERSON] et al. [4] used the Drucker-Prager yield function to simulate the compressive behaviour of AC under dynamic strain loading (strain rate from 0.0001 s\({}^{-1}\) to 0.0701 s\({}^{-1}\)). [PERSON] et al. [2] developed a microstructure-based viscoplastic continuum model to take into account the effect of temperature in AC material with the strain rate ranging from \(10^{-6}\) s\({}^{-1}\) to \(10^{-3}\) s\({}^{-1}\). Since the late 1990s, microstructural-based discrete element models (DEM) have been used for better understanding of asphalt pavement concrete (e.g., [7; 8; 9; 10]). In DEM models, the assumption of elastic or viscoelastic behaviour was employed for the simulation of the static or creep behaviour of AC under normal traffic loading. However, it was found that when the pavement structure was under blast or high impact load, plastic deformation and severe damage would occur. Thus, a robust material model should be developed to consider the strain rate effect, strain hardening, strain softening and damage of the AC material under the severe dynamic loading. Recently, several concrete-like material models subjected to dynamic loadings have been developed, such as the Riedel-Hiermaier-Thoma (RHT) model [11], the Advanced Fundamental Concrete (AFC) model [12; 13], the Karagozian and Case concrete model (KCC) [14] and the Holmquist-Johnson-Cook (HJC) concrete model [15; 16]. These robust material models are capable of capturing varying concrete-like materials' behaviour under different loading conditions. When subjected to dynamic loading, such as blast loading or high impact loading, concrete-like materials show a highly non-linear response. Besides, due to the general complexity of the constitutive models, the determination of the parameters (i.e., residual strength, failure strain and failure criteria in model) also plays an important role in achieving the actual performance of the concrete-like materials. This requires sufficient understanding of the modelling formulation and the associated considerations. In the current study, the KCC model [14] is used to simulate the AC material.