This study investigates mesoscale crack evolution and damage mechanisms in prefabricated-flaw granite specimens subjected to stepwise axial compression under multi-level confining pressures (0–20 MPa) using a real-time platform integrating micrometer-resolution X-ray CT with an in-situ triaxial loading apparatus. Three specimen configurations containing non-coplanar, parallel double flaws of equal length were tested. In-situ CT scans were performed at multiple selected loading states, enabling stage-wise tracking of crack initiation, propagation, linkage, and coalescence. Crack geometry was quantified using crack area and crack area fraction from 2-D slices, and crack volume and crack volume fraction from 3-D reconstructions. These parameters were used as stage-wise and configuration-dependent indicators of CT-resolvable open-crack geometry. The results show that increasing confining pressure strengthens flaw closure and frictional constraint, thereby elevating the initiation and propagation thresholds of opening-mode (tensile) cracks. Accordingly, the dominant cracking pattern transitions from wing-crack-driven tensile growth and rock-bridge coalescence at low confinement to a high-confinement regime characterized by densification and interconnection of low-aperture cracks, localized compressive–shear damage bands, and shear-dominated failure. Higher confinement also makes the coalescence path more tortuous and damage more localized, while markedly suppressing rock-bridge coalescence. For a representative Type S1 specimen, the crack volume and volume fraction peaked at an intermediate axial-stress stage under unconfined conditions (2.7 × 1010 μm3 and 3.0%) but decreased to 2.0 × 1010 μm3 and 2.2% at the same stage under 4 MPa confinement, highlighting the pronounced crack-closure effect of confinement on opening-crack geometry. These findings provide quantitative evidence and mechanistic insights for assessing discontinuity-controlled instability and designing hazard-mitigation strategies in deep hard-rock engineering.

The exploration and development of marine resources, as well as advances in marine research, have drawn increasing attention to the deployment dynamics of underwater facilities in complex marine environments. In this study, the descent behavior of a single-point mooring (SPM) system, which consists of a shell structure, mooring lines and gravity anchors, was investigated through a combination of experiments and numerical simulations, and the motion characteristics of the system during the descent process were analyzed in detail. As the current velocity increases, the offset distance also increases significantly. This trend becomes more pronounced at greater depths. During the initial water entry stage, the unsteady motion of the shell reduces the deviation of the anchor, reducing the final offset distance by more than 20%. In addition, the coupling effect of the load ratio and the water depth has a significant impact on the descent trajectory. Under the two water depth conditions of 30 m and 150 m, the favorable parameter range for controlling the distance offset of the structure used in this study is: flow velocity 0-0.1 m/s, load ratio 40%-60%.

Abstract: This study investigates the influence of impact sequence on cumulative damage in reinforced ultra-high performance steel fiber-reinforced concrete (UHP-SFRC) targets under multiple penetrations. Two offset penetration sequences were tested: close-range consecutive impacts (G-S-T) and long-spacing pre-impact (G-T-S). The three-dimensional damage field was characterized using acoustic wave velocity imaging and numerically reproduced via the CDPM constitutive model.Under close-range impacts, the damaged volume fraction η_V (defined as the proportion of target volume with wave velocity reduction exceeding 30%) increased from 35.49% for a single impact to 67.14% after three strikes, while the mean wave velocity decreased from 2.50 to 2.229 km/s. The long-spacing sequence produced separated multi-centered damage withη_V= 62.1% and a mean wave velocity of 2.396 km/s, with multiple intact isolation zones preserved between damage cores.Spacing analysis identifies 6D (D = 30 mm) as the complete decoupling threshold, beyond which subsequent penetration depth returns to the baseline. At 2D spacing, the subsequent projectile deviates without entering the prior cavity. In three-projectile impacts, even a decoupled second projectile creates cumulative damage with the first, allowing a third projectile within the 2D core zone to achieve stable depths of 212–231 mm (≤9% fluctuation). Consequently, the normalized parameters 2D (effective damage interaction radius) and 6D (complete decoupling distance) provide quantitative design criteria for protective structures against multiple strikes.

This study aims to clarify the mesoscopic damage evolution mechanisms of concrete subjected to rigid projectile penetration and provide support for the optimal design of high-performance protective structures. Based on the ABAQUS/Explicit finite element framework, a three-phase mesoscopic numerical model of concrete considering aggregate, mortar matrix, and interfacial transition zone (ITZ) is constructed. By combining the random convex polygon algorithm with the background mesh mapping technique, the intrinsic geometric features of stochastic materials such as crushed stone and pebble are accurately characterized. The effects of aggregate geometric characteristics, volume fraction, and projectile motion/geometry parameters (velocity, length-diameter ratio, curvature radius of the warhead CRH) on the damage evolution of the target, penetration depth, and velocity attenuation law are systematically investigated. The results reveal that increased aggregate angularity substantially enlarges both tensile and compressive damage zones and promotes crack bifurcation, which collectively enhances kinetic energy dissipation, reduces penetration depth, and accelerates projectile deceleration. Increasing the aggregate volume fraction can significantly enhance the anti-penetration resistance of the target. A high proportion of aggregate grains effectively enhances the structural toughness by blocking the crack propagation path. Penetration velocity, length-diameter ratio, and CRH are the core elements determining the penetration efficiency, and the increase in their values will lead to a significant increase in penetration depth and induce a change in the damage mode from local failure to large-scale cracking. The mesoscopic model and related conclusions established in this study can provide a theoretical foundation and numerical benchmark for the impact resistance design, optimization, and damage assessment of high-strength concrete protective structures.

The damage mechanisms of thin-walled UHPC shells subjected to underwater contact explosions remain insufficiently understood. This study conducted contact-explosion tests on air-backed UHPC cylindrical shells using 20, 30, and 40 g TNT charges and quantified damage on the blast-facing and rear surfaces through three-dimensional laser scanning. An arbitrary Lagrangian-Eulerian fluid-structure interaction model incorporating strain-rate effects was developed and validated against the experimental results. Parametric analyses were subsequently performed by varying the charge mass, shell thickness, and outer diameter, and the structural responses were normalized using the relative charge scale Πe and relative thickness Πh. The results show that the high dynamic compressive strength of UHPC suppresses localized crushing on the blast-facing surface, whereas tensile-wave reflection at the air-backed rear surface governs spalling. The first 3 ms after detonation contributed 99.19% of the cumulative pressure impulse over 0-30 ms, demonstrating that subsequent bubble evolution had a limited effect on the final damage. Increasing the charge mass promoted through-thickness damage coalescence, whereas increasing the shell thickness suppressed it; near the critical state, an 8.3% increase in charge mass triggered a transition from spalling to punching. Increasing the outer diameter weakened local restraint and enhanced global structural motion. Bending, spalling, and punching failure were distinguished in the Πe-Πh parameter space, providing a dimensionless basis for failure-mode prediction.

Recent combat conflicts such as the Russia-Ukraine war and the Lebanon-Israel conflict have shown that repeated high-precision guided weapon strikes cause severe degradation or failure of concrete structures, highlighting the urgency of researching concrete’s resistance to multiple impacts. This study investigates the damage evolution of steel fiber-reinforced concrete (SFRC) under multiple penetrations, focusing on the measurement and quantitative analysis of its mechanical performance decline.Large-scale penetration tests with three misaligned projectiles were conducted, combined with region-of-interest (ROI) Acoustic wave velocity field imaging for non-destructive testing (NDT) of 3D damage distribution (pre-penetration, post-single penetration, post-multiple penetrations). Core drilling was used to measure regional compressive strength, and a regression model correlating acoustic wave velocity with compressive strength was established. This model and measured velocity data enabled inversion analysis of SFRC strength degradation after multiple penetrations.This work achieves quantitative damage assessment of SFRC under repeated impacts, providing a critical foundation for developing penetration depth prediction formulas and cumulative damage models.

To investigate the evolution of phase structure,dislocation distribution,energy absorption capacity,and impact accumulation effect of high-entropy alloys (HEA) under shock loading,molecular dynamics simulations were employed to systematically analyze the dynamic response behavior of Al0.3CoCrFeNi HEA plate subjected to single and secondary impact load. The results show that under the first impact,the phase structure evolution and energy absorption mode of the plastic region of Al0.3CoCrFeNi HEA plate exhibits significant velocity dependence. As the velocity increases,the proportion of face-centered cubic structure shows a three-stage downward trend,while the disordered structure increases accordingly. Under low velocity impact (0.5-1.0 km/s),energy is mainly absorbed by dislocation network;at medium velocity impact (1.0-2.0 km/s),both dislocations and disordered atoms contribute;under high velocity impact (2.0-3.0 km/s),disordered atoms dominate energy absorption. Within the velocity range of 0.5-0.8 km/s of the rigid sphere,the dislocation line length increases linearly with the impact velocity. However,at higher impact velocities,the dislocation line length decreases due to the limitation of the plate thickness. The stress analysis shows that when the impact velocity increases,both the maximum stress and the boundary stress of the plastic zone exhibit nonlinear variations characterized by a quadratic relationship. Under the secondary impact,the Al0.3CoCrFeNi HEA plate forms a damage zone resembling a trapezoidal shape after impact. The radius of the pit within this damage zone exhibits a quadratic relationship with the impact velocity. Additionally,the minimum affected area resulting from the secondary impact also demonstrates a quadratic relationship with the impact velocity.Regarding impact resistance,as the initial impact velocity increases,the residual velocity following the secondary impact also rises,indicating a reduction in the resistance capability of HEA. At a distance of 10 nm from the impact center,the ballistic limit velocity decreases nonlinearly with increasing initial impact velocity. However,an increase in the secondary impact velocity mitigates the effects induced by the initial impact.

Existing mesoscopic numerical models still exhibit shortcomings in terms of the aggregate geometric fidelity, interface transition zone (ITZ) characterization, and modeling efficiency. To solve these problems, this paper establishes a two-dimensional mesoscopic model and analysis method for concrete, considering randomly distributed convex polygons of aggregate grains and a three-phase structure comprising aggregate, mortar, and ITZ. An efficient random placement algorithm based on background meshing is proposed to enable rapid and accurate model construction. The effects of aggregate geometry, spatial distribution, and ITZ on mechanical properties and damage evolution have been systematically studied. A quantitative relationship has been established between damage energy and the decay of strength and stiffness, and damage quantification indices have been proposed. The damage rates of mortar and ITZ, along with the variation characteristics of the damage variable dc at each stage, have been quantified. Neglecting the ITZ leads to overestimation of the peak strength and stiffness of concrete while exacerbating its post-peak brittle behavior. The most significant increases occur in both stiffness decay and damage growth at 90% of peak stress. A sudden change occurs at approximately 0.17% axial strain (corresponding to 80% of peak stress). This study offers a meso-scale foundation for understanding concrete failure and designing high-performance concrete.

Laboratory blasting tests on granite were conducted under varying confining pressure conditions. Damage data across blast crater cross-sections in various directions were obtained using 3D laser scanning and image processing techniques and systematically analyzed based on fractal theory to characterize damage morphology and spatial distribution. The directional anisotropy of blast-induced rock damage was investigated, along with the spatial heterogeneity evolution of damage cross-sections in the direction of applied confinement. The research results indicate that confining pressure significantly regulates the spatial distribution of explosive damage in rock. Under no confining pressure, damage propagation is primarily governed by the intrinsic heterogeneity of the rock, resulting in an approximately isotropic distribution of blast-induced damage, as indicated by a low coefficient of variation of 0.159. Under asymmetric biaxial confining pressure, the cross-sectional damage exhibits a stress-direction-dependent deflection and a redistribution of damage complexity. This phenomenon is herein defined as the “inductive deflection” effect. Lower equal biaxial confining pressure enhances the dominant role of the rock’s heterogeneous structure in the damage evolution path, resulting in differences in the degree of damage across different directional cross-sections. Higher equal biaxial confining pressure suppresses the expansion of damage along the free surface and redirects damage development toward greater depths, resulting in a 21.4 D reflects the regulatory effect of confining pressure on the “propagation mode” of the damage, while the intercept A is directly related to the “spatial occupancy rate or coverage” of the damage. Both are crucial parameters for describing the effects of rock blasting and for assessing the regulatory role of confining pressure on explosive damage.

Stress wave propagation to the ground surface undergoes amplification and attenuation effects due to the complex surface topography. However, current research tends to analyze the influencing factors, with limited attention paid to the mechanical mechanisms behind these topographic effects. This study aims to investigate the mechanical mechanism of underground explosion-induced wave propagation in rock medium under different topographies from a particle scale and force chain perspective. The discrete element method (DEM) was employed and developed to capture the wave propagation and reflection behavior. The explosive source set in DEM models was equated to the velocity–time history applied to the cavity wall particles based on the calculation of Autodyn. The validity and reasonableness of the adopted modeling and simulation methods in this study are confirmed. Three representative rock mass topographies were generated in the present study: A semicircular hill, a semicircular hollow, and a flat surface. From the simulation results, the ground motion amplification phenomenon is found on the surface of hill topography and the ground surface adjacent to the hollow topography during the underground explosion processes. Besides, the ground motion attenuation phenomenon is found on the surface of hollows and the corners of the edge of hills and hollows. The wave conversion phenomenon of P-wave reflection was observed in the DEM simulations from the velocity and force-chain fields. Meanwhile, the mechanical mechanism of topographic effects in the rock medium was discussed by the spatial distribution and evolution of the mean compressive and tensile forces of the force chain. Besides, the difference in mean tensile force and energy storage and dissipation between these three topographies during the wave propagation and reflection process was analyzed. This work provides a reference for the discrete medium approach to modeling and capturing explosion-induced wave propagation behavior. Simulation results are beneficial for further understanding the mechanical mechanism of amplification and attenuation effects during wave propagation in different rock mass topographies.

Deep tunnel excavation and mining operations are commonly subjected to the coupled effects of high in-situ stresses and blasting loads, under which the pre-existing static stress state can markedly govern blasting-induced rock breakage and excavation efficiency. Meanwhile, in complex blasting and excavation settings, robust delineation of the post-blast-damaged zone and quantitative characterization of its geometric complexity remain challenging. To clarify how confinement regulates blast-induced damage in rock, this study conducted blasting experiments on granite under a series of confining-stress conditions. First, a 3D point-cloud-based damage-identification approach was developed to extract the damaged region under complex surface backgrounds and to provide high-quality image data for subsequent analyses. Second, a “Dynamic selection method based on ddual-criterion and edge penalization” (DS-DCEP) was established to determine the scale-free interval for fractal-dimension estimation, thereby improving the accuracy and stability of fractal characterization. On this basis, the blast-induced damaged zones were subjected to fractal analysis. The results show that confinement significantly alters the damage distribution pattern and evolution path by regulating the stress field around the blasthole: uniaxial confinement strengthens damage directionality, asymmetric biaxial confinement promotes localized damage concentration and more pronounced anisotropy, whereas elevated equal biaxial confinement markedly suppresses damage expansion, leading to a convergent and relatively homogenized damage distribution. Moreover, the fractal dimension, as a key quantitative descriptor of damage complexity, not only captures the geometric attributes of rock damage but also reveals the intrinsic distinction between damage extent and complexity, offering unique advantages for anisotropy assessment and failure-mechanism identification. Overall, this work establishes a damage-identification and fractal-characterization framework for complex scenarios, elucidates the confinement-dependent evolution of blasting damage and anisotropy, and provides quantitative support for parameter optimization and safety assessment in deep blasting engineering.

The study aims to solve the problem of calculating the thickness limit of high-strength steel-concrete composite structures under the impact of slender thin-walled projectiles, a key consideration for protective engineering design. A series of impact tests on composite targets were carried out. These targets were composed of different high-strength steel plates and concrete backplates. Slender thin-walled projectiles were launched with a gas gun at controlled velocities, and the impact process were captured by high-speed cameras. The resulting damage to the structures and the failure modes of the projectiles were analyzed using both non-destructive and destructive testing methods. Based on test results, the protective mechanism of the composite structures and the failure modes of projectiles were analyzed. An improved thickness limit calculation model was then developed. Unlike the original model, this new model incorporated the structural strength of slender thin-walled projectiles, considering their wall thickness, material yield strength, and geometric dimensions, and was established based on force equilibrium and energy conservation principles. The results show that the high-strength steel in the composite structures provides material strength to resist penetration, while the concrete backplate offers support stiffness. As slender thin-walled projectiles are prone to compression and expansion cracking during impact, their structural strength must be factored into the calculation model. Moreover, the design of composite structures should consider both the mechanical properties of high-strength steel and the thickness limit. In conclusion, though the proposed model offers a new theoretical approach, it has limitations such as empirical parameters and conservative results. Further research is necessary to refine and enhance the model. The study's findings provide a theoretical basis for the design and application of high-strength steel-concrete composite structures in protective engineering.

Fragment velocity is a critical parameter for assessing the damage potential of cased charges, and its accurate prediction has been a focal point in the field of engineering protection. To develop a more widely applicable and accurate fragment velocity calculation formula, this study integrates experimental and numerical simulation results to construct an artificial neural network (ANN) predictive model for the spatial distribution parameters of fragment velocity. Based on this, a calculation formula that considers spatial distribution parameters and fragment velocity distribution is derived. The results indicate that fragment velocity is positively correlated with the charge mass ratio, end cap thickness ratio, and aspect ratio, with the mass ratio having the most significant impact. The spatial distribution parameter is negatively correlated only with the end cap thickness ratio. The developed fragment velocity formula yields an average error of 6.2 % for the charge with end caps and 4.4 % without end caps, reducing the average error by 3.9 % and 1.1 %, respectively, compared to the formula established by Liao et al. Overall, the neural network model developed in this study effectively predicts spatial distribution parameters of fragment velocity, and the resulting fragment velocity formula offers broad applicability and enhanced accuracy.

The properties of oxidants significantly affect the thermal and combustion properties of nanothermites, and alpha and beta-MnO2 nanorods with similar morphological appearances were prepared using the hydrothermal method. Corresponding nanothermites were prepared employing the electrostatic spraying method and their thermal and combustion properties have been compared through TG-DSC and combustion tests. The aluminothermic reaction process was simulated by molecular dynamics, and the results showed that the β-MnO2/Al nanothermite first underwent β-MnO2 thermal decomposition followed immediately by an aluminothermic reaction, whereas the α-MnO2/Al nanothermite underwent a direct aluminothermic reaction. In contrast, the α-MnO2/Al nanothermite could release more heat. According to thermal analysis, the activation energy of α-MnO2/Al nanothermite was 100.15 kJ mol− 1 higher than β-MnO2/Al nanothermite, indicating better stability. Combustion experiments showed that the combustion propagation rate of the α-MnO2/Al nanothermite was faster than the β-MnO2/Al nanothermite. The results have been verified and the reaction process has been exhibited using molecular dynamics to simulate the aluminothermic reaction process. The notable differences in the thermal and combustion properties of nanothermites containing MnO2 with varying phases can be attributed to the distinct crystal structures of α-MnO2 and β-MnO2. The alternating 1 × 1 and 2 × 2 tunnel structure of α-MnO2 is more stable, whereas β-MnO2 undergoes thermal decomposition before the aluminothermic reaction.

In this work, the micro-deformation mechanisms and coupling regularities in a polycrystalline gradient shortrange ordered Al0.3CoCrFeNi high-entropy alloy (HEA) were systematically investigated at high strain rates via molecular dynamics simulations with a novel analytical method that integrates crystal orientation tracking and grain boundary motion vector decomposition. The results show that the HEA exhibits a complex and synergistic deformation behavior at high strain rates. Within the grain interiors, a large number of stacking faults slip activities are observed, whereas deformation twins occur predominantly in larger grains. Dislocations are found to preferentially nucleate and accumulate at grain boundaries and subsequently propagate into the grain interiors as strain increases. Concurrently, the grains undergo a series of dynamic processes, including rotation, elongation, fragmentation, as well as grain boundary migration and sliding. Furthermore, a three-stage evolution model of the microscopic mechanism, regulated by strain rate, is established: at lower strain rates, deformation is primarily governed by stacking fault slip, coordinated by the rotation of smaller grains. At moderate strain rates, the mechanism transitions to a dynamic equilibrium between dislocation activity and twinning. At high strain rate, the formation of Disorder phase becomes the dominant mechanism. Additionally, the study also reveals that there is a reverse evolution relationship between grain rotation and slip distance depending on grain size. These findings not only deepen the scientific understanding of the dynamic deformation behavior of HEAs but also provide a crucial theoretical basis for the designing HEA with superior resistance to high-velocity impact.

The presence of joints can significantly reduce the integrity and stability of an engineering rock mass. Under dynamic loads, such as from blasting excavation, the key blocks divided by joints may be destabilized and prone to sliding, potentially leading to engineering geological disasters like rockbursts. To study the dynamic instability process, similar materials for the rock mass and joints were developed based on the similarity theory, and a tunnel model in the jointed rock mass was constructed. Subsequently, a detonating fuse was used to generate a dynamic load, and the dynamic instability process of the tunnel surrounding rock in the jointed rock mass under explosive load was studied using the geotechnical multifunctional testing device. The deformation characteristics and dynamic instability process of the tunnel surrounding rock were analyzed using acceleration sensors, resistance strain gages, linear variable displacement transducers and motion camera. The study shows that the acceleration at the tunnel vault is significantly greater than at the straight wall and floor under blast loads, with differences reaching an order of magnitude. Acceleration waveforms were classified into three categories based on peak characteristics, explained through the propagation of explosive stress waves. Additionally, strain and displacement at the tunnel arch were also significantly greater than in other areas, indicating more severe stress concentration and dynamic damage at the arch, necessitating reinforced support in tunnel excavation. The entire dynamic instability process of the tunnel surrounding rock was successfully recorded using a motion camera. The dynamic failure process was divided into several phases, the appearance of cracks on the joint surface, particle ejection accompanied by the dropping of jointed blocks, a significant drop of the jointed blocks, and return to calm. The dynamic failure modes include the dropping and rotation of jointed blocks, local particle ejection, and shear cracks on jointed block.

In recent years, with the increasing use of reinforcement and widespread use of ultra-high performance concrete (UHPC) materials in concrete structures, it is difficult to accurately calculate the penetration depth of these concrete structures by existing formulas. To develop a universal formula applicable to all types of concrete structures, this paper investigates and evaluates existing formulas for calculating the penetration depth of concrete structures. Based on these formulas, we derive a new expression considering the volume reinforcement ratio and a preliminary form of the universal formula. Two penetration tests were conducted on a normal concrete structure and an UHPC structure, followed by the establishment and validation of two numerical models based on the test results. According to regression analysis and linear interpolation methods, we determine the reinforcement ratio impact factor (alpha) in the new expression, yielding the final form of the universal formula. Finally, validation with 26 sets of test data and comparison with existing formulas demonstrate that the proposed formula in this paper offers higher calculation accuracy and better universality. The calculation formula presented in this paper is applicable not only to normal concrete structures but also to UHPC structures. This formula holds significant reference value for the protective design of concrete structures, providing a basis for evaluating the anti-penetration performance of concrete structures.

Currently, research on the anti-penetration performance of freeze-thaw concrete is virtually nonexistent, with little to no empirical or exploratory work conducted in this area. To address this gap, this paper systematically investigates the anti-penetration performance of freeze-thaw concrete through a combination of penetration tests and numerical simulations. Initially, penetration tests were conducted on concrete targets subjected to 0-125 freeze-thaw cycles to phenomenologically analyze the impact of freeze-thaw cycles on penetration resistance. Subsequently, a modified strain-rate effect curve for freeze-thawed concrete was implemented in the calibration of K&C model parameters. Numerical models with both uniform and heterogeneous strength distributions were developed to analyze the influence of freeze-thaw cycles on the anti-penetration performance of concrete. Finally, an empirical relationship describing the degradation of concrete strength due to freeze-thaw was proposed and integrated with the existing penetration depth formulas. The study revealed that as the number of freeze-thaw cycles increased, the penetration depth exhibits a monotonic increase, whereas the pit area demonstrates a non-monotonic but generally upward trend. Freeze-thaw cycles are found to influence the anti-penetration performance by diminishing the compressive strength of concrete and increasing the strength heterogeneity. The reduction in compressive strength significantly affects both the penetration depth and the pit area, while the increased strength heterogeneity has a minimal effect on penetration depth but a notable effect on the pit area. Forrestal formula, in conjunction with the proposed empirical relationship describing the degradation of concrete strength, provides the most accurate prediction of penetration depth in freeze-thawed concrete. These findings provide valuable reference for the design of protective concrete structures in cold regions, and offer important experimental data and numerical simulation methods for further research on the penetration resistance of freeze-thaw concrete structures.

To gain an in-depth understanding of the coupled damage characteristics of preformed fragments and shock waves on concrete walls, and to provide effective reference data, it is particularly important to carry out field tests. In this paper, the explosion test of preformed fragment warheads was designed and carried out to investigate the effects of wall thickness, strength and stand-off distance on the damage effects of reinforced concrete (RC) walls and plain concrete (PC) walls under the combined loading of preformed fragments and shock waves. The severe damage characteristics of the preformed fragments warhead are revealed by setting up two sets of bare charge explosion comparison tests. The results show that the shock wave generated by the explosion of a preformed fragment warhead propagates in the form of a spherical wave, and the spatial distribution of the fragments exhibits significant directional, with fragments near the detonation end scattering downward, while most other fragments scatter upward. Compared with bare charge explosions, the preformed fragment warhead causes more significant damage to concrete walls, with local damage caused by fragment penetration being the key factor in exacerbating overall damage. In the design of protective engineering, in addition to considering the penetration effect of fragments, attention should also be given to the dynamic effect of stress waves on structures. Furthermore, the damage evaluation method based on a single mechanical parameter (such as rotation angle and deflection) cannot accurately represent the composite damage pattern of structures under the combined loading of fragments and shock waves, and there is a need to further establish coupled damage criteria for fragments and shock waves.