Contact With Hole Under Explosion Load Protection Structure Damage Effect Research

Protective structures are engineering structures that are used to resist destructive weapons. Protective structures used in field operations are often constructed by steel and concrete, and different sizes of holes are set for shooting, watching, ventilation and access. The damage effect to protective structures with holes by contact explosion reflects in two aspects. First, the powerful blast wave produced by contact explosion enters into protective structures through holes and it hurts the staff and damages the facilities. Secondly, contact explosion damages the reinforced concrete walls of protective structures, even makes the walls penetrated and the structures collapsed. Once the staff inside the protective structures with holes hurt badly, or the reinforced concrete walls of protective structures are penetrated, the protective structures are considered to be ineffective.Based on theoretical analysis, the propagation laws of shock waves around the protective structures and the damage effect to RC walls under contact explosive loads have been studied by means of numerical calculation. The following results have been achieved:1. Based on aerodynamic theory, combined with AUTODYN numerical simulation, the propagation phenomenon and law of shock waves around the protective structures with holes under contact explosive loads have been analyzed, and the determination method of loads of shock waves on walls and the formula of air pressure inside the protective structures have been proposed.2. Based on the widely-used cavity expansion theory, this paper has studied on the calculation method of characteristic parameters in explosion zones and the formula of max damage radius has been derived. Also, the anti-tearing mechanism of steel bars and the stress concentration around steel bars have been revealed.3. The state equations and constitutive models of the materials (air, explosive, concrete and steel bar) involved in the research have been summarized. The adaptability of state equations and constitutive models is verified by comparing the experiment data with the numerical simulation data.4. The propagation of shock waves around the protective structures and the failure models of RC walls under contact explosive loads have been simulated by AUTODYN. By comparing the overpressure in different conditions, the propagation laws and characteristic parameters of shock waves inside the protective structures have been analyzed. And based on the data of numerical calculation, the prediction formulas of characteristic parameters have been achieved. Besides, this paper has revealed the relationship between TNT equivalence and the damage of reinforced concrete targets.