Ultra-high-performance concrete (UHPC) is a cement-based material with excellent impact resistance. Compared with traditional concrete, it possesses ultra-high strength, ultra-high toughness, and ultra-high durability, making it an ideal material for designing structures with impact resistance. The research on the impact resistance performance of UHPC and its composite structures is of great significance for the structural design of protective engineering projects. However, currently, there is still insufficient research on the impact resistance performance of UHPC composite structures. To study the impact resistance performance, experiments were conducted on UHPC targets using high-speed projectiles. The results were compared with impact tests on granite targets. The results indicated that when subjected to projectile impact, the UHPC targets exhibited smaller surface craters compared with the granite targets, while the penetration depth was lower in the granite targets. Afterwards, the process of a projectile impacting the UHPC composite structure was numerically simulated using ANSYS 16.0/LS-DYNA finite element software. The numerical simulation results of penetration depth and crater diameter were in good agreement with the experimental results, which indicates the rationality of the numerical model. Based on this, further analysis was carried out on the influence of impact velocity, impact angle, and reinforcement ratio on the penetration depth of the composite structure. The results show that the larger the incident angle or the smaller the velocity of the projectile is, the easier it is to deflect the projectile. There is a linear relationship between penetration depth and reinforcement ratio; as the reinforcement ratio increases, the penetration depth decreases significantly. This research is of great significance in improving the safety and reliability of key projects and also contributes to the application and development of ultra-high-performance materials in the engineering field.

A total of 9 tests were carried out with 30 mm and 78 mm caliber scaled projectiles penetrating into granite targets. The penetration depth, crater diameter, and mass loss rate were examined and discussed. The results indicate that the dimensionless penetration depth of large-caliber projectiles is 20% greater than small-caliber projectiles. Based on the description of static resistance R_a in the Forrestal semi-empirical formula, the size effect of dimensionless penetration depth can be attributed to the size effect of static resistance R_a, and it can be seen that the penetration static resistance of projectile A is 40% higher than that of projectile B. Numerical simulations of projectile penetration into granite targets were conducted using the finite element program ANSYS/LS-DYNA. In terms of penetration depth and crater damage, the numerical simulation results agree well with the test data. This suggests that the selection of parameters was reasonable. The influence of compressive strength, projectile striking velocity, mass, diameter, and caliber–radius–head (CRH) ratio on the static resistance R_a were studied by RHT model parameterization. Based on the numerical results from the parametric study, an empirical formula was derived to predict the static resistance R_a.

In this paper, the straight-wall-arch structure in the rock medium is taken as the research object, and the high-pressure plane charge loading test technology is adopted to study the anti-explosion performance of different types of structures under the explosion loading. Three types of structures, which are individually built with the high-performance reinforced concrete, the C30 reinforced concrete, and the C30 reinforced concrete with a foam concrete backfill layer as well, are tested, and the dynamic responses and damage characteristics of these structures are investigated. The test results show that under the condition of the same plane charge explosion loading, in the vault of the high-performance reinforced concrete test section appears a through-tensile crack with a largest transverse relative displacement between the two straight walls, and the composite structure test section only shows an intermittent crack at the arch foot, which represents a slight damage mode. Meanwhile the arch spring of the C30 reinforced concrete test section suffers a through-compression shear failure with a largest vertical relative displacement between the vault and the floor, which represents a moderate damage mode. Therefore, adopting the high-performance reinforced concrete, and the C30 reinforced concrete with the foam concrete backfill layer, can effectively decrease the damage degree of the rock structures. Compared with the C30 reinforced concrete, the high-performance reinforced concrete can improve the resistance of the structure by improving the structural strength and strengthening its capacity to absorb waves and energy dissipation, and the foam concrete backfill layer can significantly reduce the lateral and vertical relative displacement of the structural free surface and the peak stress of the structural inner layer. The composite structure test section of the C30 reinforced concrete with foam concrete backfill layer appears to be an excellent anti-explosion performance property.