A novel hydro-elastoplastic constitutive model incorporating hydrostatic damage for predicting high-pressure performance of concrete under blast loading

The evolution of damage and failure modes of concrete under blast or impact loads are the outcomes of stress wave propagation. The stress state at a point within the concrete changes instantaneously with time and space. Establishing a constitutive model that can cover the nonlinear behavior of materials under complex loading paths and histories is an extremely challenging task. The main difficulty lies in the construction of the damage model, which has not yet been fully resolved in commonly used concrete models. This paper, based on the mechanisms of damage and failure of concrete under hydrostatic pressure, constructs a state equation that includes the description of crushing and compaction damage due to the collapse and closure of pores, as well as their interactive model, negative pressure degradation caused by hydrostatic pressure, and nonlinear volumetric behavior under loading/unloading/reloading. By introducing independent shear and tensile deviatoric damage scaling functions and a damage scaling function under isotropic tension, the coupling relationship between deviatoric and volumetric damage is considered. Corresponding strength models and element erosion criteria are developed based on the new state equation and damage models. Then, single-element numerical experiments of unconstrained uniaxial compression and tension, triaxial compression under different confining pressures, monotonic and cyclic hydrostatic compression, and isotropic tension were conducted to verify the predictive accuracy of the proposed model under single loading paths. Finally, numerical experiments of contact explosion on plain concrete thick and thin targets were carried out using the proposed model, revealing the propagation laws and failure processes of the loading compression wave, unloading tensile wave, and reflected tensile wave within the concrete target. The predicted final failure modes are consistent with the experimental results.