Repetitive low-level blast overpressure exposure is an increasingly recognized occupational hazard for military, law enforcement, and specialist breaching personnel. Unlike high-level blast exposures that commonly result in overt traumatic brain injury, acute low-level blast events have not been demonstrated to produce clinically detectable concussion or neurological injury in isolation. Nevertheless, growing concern has emerged that repeated low-level blast exposure may impart cumulative biomechanical stress, capable of producing biologically and clinically meaningful adverse brain effects over time. This narrative review synthesizes human epidemiological, clinical, neuroimaging, and biomarker evidence published between 2010 and 2025, regarding the neurological impact of repetitive low-level blast exposure. We review exposure contexts and operational epidemiology, blast physics, and candidate mechanistic pathways, including axonal and glial stress, cerebrospinal fluid–tissue interface effects, and blast-related vascular perturbation with blood–brain barrier dysfunction, that are supported by converging human translational findings. Clinical manifestations are examined across cognitive, vestibular, oculomotor, auditory, headache, and psychological domains, highlighting the subtle, cumulative, and often subclinical nature of observed effects. We further evaluate emerging fluid biomarkers and advanced neuroimaging modalities that provide evidence of astroglia activation, axonal stress, neurovascular perturbation, and network-level dysfunction in occupationally exposed cohorts. Importantly, current evidence does not demonstrate that repetitive low-level blast exposure alone is sufficient to cause neurodegenerative disease. Rather, findings support a model in which cumulative low-level blast may act as a modifier of neural vulnerability, particularly in individuals with mixed exposure histories or additional risk factors. We conclude by identifying critical gaps in exposure quantification, longitudinal data, and dose–response modeling, and discuss implications for future research and occupational brain-health surveillance.

The design of blasting parameters for open-pit mines mainly relies on empirical analysis, which leads to problems such as poor blasting effect and high randomness. Conduct research on intelligent optimisation schemes for open-pit mine bench blasting parameters by combining mathematical analysis and numerical simulation methods. The specific research process mainly includes the following aspects. Based on rock mechanics experiments, obtain the mechanical parameters of ore and rock in the blasting area on-site. Constructing a prediction model for open-pit mine bench blasting and an intelligent optimisation scheme for blasting parameters based on the KUZ-RAM model. Considering the actual production of open-pit mines, and combining LS-DYNA to establish a detailed blasting simulation, a basic 3D model is used. Establish a simulation parameter scheme suitable for open-pit mine bench blasting to conduct numerical simulation research. Comparing the numerical simulation results with the actual blasting effect on site, with the goal of mining blasting fragmentation and blasting vibration, the optimisation plan for open-pit mining bench blasting parameters is verified. Practical application was carried out in Qidashan open-pit mine, a computer vision and blasting vibration analysis system was used to collect and analyse on-site data. The production operation was carried out according to the optimised hole network parameters, which significantly improved the blasting effect of Qidashan open-pit mine. The annual average cost of drilling and pyrotechnic equipment was saved by about 11.85 million yuan, verifying the feasibility and effectiveness of the research plan.

ABSTRACT To investigate the effects of delay blasting on crack propagation in a defective empty hole, this study employed dynamic caustics experiments and numerical simulation to analyze crack propagation behavior and stress distribution. The results show that the stress waves' superposition enhances dynamic mechanical parameters (including crack propagation velocity, dynamic stress intensity factors [DSIFs], and energy release rates) at the crack tip, especially during the initial phase. When boreholes are detonated simultaneously or when the borehole near the empty hole is detonated first with a short delay, the interaction between the stress waves from the remote borehole and the running crack significantly enhances dynamic mechanical parameters and promotes crack propagation. When the delay time is long, the stress waves from the remote borehole can induce the crack to initiate again, and the dynamic mechanical parameters are higher than in the first phase. Additionally, because of the diffraction of stress waves in the empty hole, the hoop tensile stress on the back blasting side initially increases and subsequently decreases with increasing distance. These research results provide a reference for optimizing delay times and improving rock breaking efficiency.

Repeated exposure to blast overpressure in occupational settings has been associated with changes in cognitive and psychological health, as well as deficits in neurosensory subsystems. In this work, we describe a wearable system to simultaneously monitor physiology and blast exposure levels and demonstrate how this system can identify individualized exposure levels corresponding to acute physiological response to blast exposure. Machine learning was used to develop a dose-response model that fused multiple physiological measures (electrooculuography, gait, and balance) into a single risk score by predicting the level of blast exposure on held-out subjects (Fused model, R = 0.60). For our system, cohort, and environment, we found that blast events with peak pressure levels as low as 0.3 pound per square inch (PSI) could be related to physiological changes with blast exposure. We also identified an individual subject with longitudinally increasing reaction time scores who consistently showed a rapid and anomalous change in physiology-based risk scores after exposure to low-level blast events. Our results suggest that wearable technology may be viable for measuring physiological changes that are related to occupational blast exposure. Ultimately, this approach might be used to prevent neurotrauma from repeated exposure and to help set limits for a population or on an individual basis.

Hemorrhage remains the leading preventable cause of trauma mortality. Blast trauma combines primary blast effects with complex secondary and tertiary injuries, precipitating profound hemodynamic instability and microcirculatory disruption. While intramuscular (IM) arginine vasopressin (AVP) stabilizes arterial pressure in isolated hemorrhagic shock, vasopressin’s efficacy in blast-associated hemorrhagic shock is unknown. In a randomized, blinded study, 22 swine underwent femoral blast injury and controlled class II hemorrhage. Animals received IM AVP 40 U (two doses 60 min apart due to short half-life and transient effects; n = 5), IM terlipressin 2 mg (n = 5), intravenous (IV) terlipressin 2 mg (n = 5), or saline control (n = 7). All subjects received a 500 mL autologous whole blood transfusion and were observed for 120 min. The primary outcome was systolic arterial pressure (SAP). Secondary outcomes included systemic vascular resistance index (SVRI), cardiopulmonary and metabolic variables, and serum AVP to assess IM uptake. IV terlipressin rapidly stabilized hemodynamics, increasing SAP (mean difference 24 mmHg, p = 0.01) and SVRI (mean difference 44593 dynes·s·cm⁻⁵·kg, p = 0.004) versus controls, and increased mixed venous oxygen saturation and urine output. Respiratory and metabolic variables were similar across groups. Neither IM AVP nor IM terlipressin generated a meaningful pressor response. IM AVP absorption was profoundly variable and did not reliably translate into hemodynamic stabilization; only one animal demonstrated both high systemic uptake and a sustained response. In blast-associated hemorrhagic shock, IV terlipressin provided consistent hemodynamic stabilization, whereas IM vasopressin analogues were unreliable, highlighting a critical limitation of the IM route in blast pathophysiology. Preclinicaltrials.eu, PCT ID: PCTE0000548, Registration date: 30 October 2024.

The reasonable delay time setting is the key factor affecting the blasting effect of gas tunnel. To this end, we have introduced a digital electronic detonator that can be freely set on site. Through theoretical analysis, we obtained the time required for the rock mass to be completely thrown out in the cutting area, revealed the law of rock mass movement by numerical simulation, and further proposed a blasting effect evaluation method and carried out engineering application. The results show that the optimal initiation time of the cutting area is 40ms, and the migration law of rock mass can be divided into three stages: crack propagation, volume increase and rock mass ejection. According to the optimal delay time in the cutting area, the optimal initiation time between each row of blast holes was determined to be 0ms, 40ms, 60ms, 80ms, 100ms, and 120ms, respectively, and a blasting effect evaluation system including blasting effect index K and circumferential flatness σ was established. Finally, a field test was carried out in a plateau gas tunnel. The statistical characteristics of the blasting effect show that after optimizing the delay time, the half-hole rate after blasting is above 90%, the linear average over-excavation is within 20cm, and the circumferential flatness σ is 2.9cm. The contour control accuracy is high, and the particle size distribution of the blasting pile is reasonable, which provides a reference for similar engineering blasting.

This study employs both experimental and numerical methods to investigate the blast resistance of ceramic fiber-reinforced geopolymer concrete (CFGC), a cement-free material often referred to as green concrete due to its environmentally friendly nature compared to Portland cement concrete (PCC). Geopolymer concrete specimens, formulated with ground granulated blast furnace slag, silica fume, and varying proportions of ceramic fibers, were subjected to blast tests using 50, 100, 150, 200, and 250 grams of trinitroglycerin (TNG). A standard PCC specimen was utilized as a control. The results demonstrate that the incorporation of 10% ceramic fibers significantly enhances the blast resistance of the geopolymer concrete, reducing crater diameters by up to 20% compared to conventional PCC. Furthermore, the finite element model developed in ANSYS Workbench exhibits a strong correlation with the experimental data, validating the predictive capability of the numerical simulations. Overall, this research highlights the immense potential of CFGC as a sustainable, highly durable alternative for structures exposed to blast loads.

Towards rapid prediction of TNT blast-Induced primary and secondary human injuries in urban environments

Abstract The prevailing global political circumstances and the concomitant increase in security concerns give rise to heightened expectations regarding the building envelope.Transparent areas in façades are essential for daylight entrance and the interaction between the interior and the external environment but represent a risk to building occupants in the case of blast events or attack with firearms. Conventional glazing such as monolithic glazing and laminated safety glass lack resistance to bullet attack due to their brittle fracture behaviour. Glass shows favourable properties in terms of scratch resistance and strength. While the lamination of numerous layers of glass panes provides enhanced resistance against bullet attack, higher dead weights result, necessitating thicker frames and fittings. Due to the higher ductility of polymers, the integration of glass with polymeric glazing material effectively reduces the total dead weight and nominal thickness of security glazing with a resistance against bullet attack. The classification of bullet-resistant glazing is determined in accordance with European standard EN 1063. A test specimen is subjected to a series of three shots fired in a triangular configuration using specified types of weapons and ammunition. The present paper focuses on the topic of bullet resistance by glass panes, plastic sheets and composite panels. In initial experimental tests, monolithic test specimens of annealed glass, toughened safety glass, polycarbonate sheets and polymethylmethacrylate sheets are investigated. The thicknesses of the materials are in a range that will cause a bullet to penetrate. This enables to measure the velocity before and after penetration of the test specimen, as well as to calculate the absorbed energy. Finally, the materials can be characterised in the context of ballistic impact. By recording the mass of the outgoing fragment and the projectile using ultra-high-speed imaging, it is possible to analyse the effect of the materials on velocity reduction. The combination of individual layers with and without lamination by thermoplastic polyurethane interlayers allows for the recommendation of a favourable composition in the cross-section. As result of the research, bullet-resistant glazing with reduced nominal thicknesses can be predicted and processed to slim insulated glazing with high thermal insulation.

In underground construction, the drilling and blasting method is widely used due to its advantages, such as low cost, simple implementation, and applicability under various geological and hydrogeological conditions. One parameter that significantly affects the effectiveness of drilling and blasting is the post-blast tunnel cross-sectional area. In this study, multiple linear regression analysis (MLRA) and multiple nonlinear regression (MNLR) models were used to predict the area of a tunnel face after blasting, utilizing 136 datasets containing parameters measured from the tunnel face area after blasting during the Deo Ca tunnel construction project. Three deep learning models, an artificial neural network (ANN) and two hybrid models combining an ANN with the particle swarm optimization (PSO) algorithm and an ANN with a genetic algorithm (GA), were then developed to predict the tunnel face area after blasting. The input variables for the calculation and prediction models included the designed tunnel face area (Sd), the specific charge (SC) of the explosion, the average borehole length (L), and the rock mass rating (RMR) of the rock mass on the tunnel face. The GA-ANN model’s results, including determination coefficient (R2) and mean square error (MSE) values of R2train = 0.9562, R2testing = 0.94, MSEtraining = 0.0156, and MSEtesting = 0.0302, indicate that it provides a better prediction of the tunnel face area after blasting than the other models.

Service members are frequently exposed to low-level, repetitive blast waves, raising concerns about potential brain injury. A New York Times video, "How Blast Waves Affect Troops' Brains," used a dramatic analogy of a beer bottle shattering under impact to illustrate the effects of blast waves on the brain. Although this analogy raises awareness, it may oversimplify and misrepresent the biomechanics of blast-related injuries. Our research, employing high-speed optical diagnostics and biofidelic tissue simulants, does not support the claim that a single, violent wave propagates through the brain at blast levels typical of routine military exposures. Instead, our findings using the Anthropomorphic Neurologic Gyrencephalic Unified Standard (ANGUS) phantom indicate that blast-induced injuries are more nuanced, often involving cavitation and high strain rates at intracranial tissue interfaces, such as the perivascular and periventricular regions. Computational models and acoustic imaging further confirm localized cavitation dynamics rather than a singular destructive wave. The portrayal in the New York Times video, akin to the dramatization of chronic traumatic encephalopathy in the movie Concussion (2015), risks misinforming the public and policymakers. Future research leveraging ultra-high-performance neuroimaging, such as our Microstructure Anatomy Gradient for Neuroimaging with Ultrafast Scanning (MAGNUS) system, may provide a more precise assessment of cumulative blast effects. By presenting a balanced and scientifically grounded perspective, we aim to contribute to the accurate depiction of blast-related neurotrauma and inform strategies for mitigating risks and protecting warfighter brain health.

To reveal the cumulative damage mechanism of surrounding rock with initial damage under cyclic blasting loads during tunnel reconstruction and expansion, this study combines theoretical modeling, split Hopkinson pressure bar (SHPB) tests, and three-dimensional numerical simulation. First, based on the Z-W-T model framework, a dynamic damage constitutive model capable of uniformly describing the coupling effects of initial damage and dynamic disturbance is constructed by introducing a damage evolution equation based on the Weibull distribution and an initial damage variable D0. Second, SHPB impact tests are conducted on sandstone specimens with different D0 values under various strain rates to obtain their dynamic mechanical responses. The model parameters are calibrated and its validity is verified. Finally, the validated model is implemented in ABAQUS via a user material subroutine to establish a 3D finite element model of the tunnel reconstruction and expansion, and a numerical test with seven cyclic blasting events is performed. The results show that the dynamic compressive strength of the surrounding rock increases significantly with increasing strain rate, but D0 has a clear weakening effect, which is amplified under high strain rates. Numerical simulation reveals that the damage in the surrounding rock accumulates nonlinearly with the number of blasts. The incremental expansion of the damage zone after the first blast is 1.51 m, decreasing to 0.03 m by the seventh blast, indicating a successively diminishing incremental expansion per blast. This reflects the saturation characteristics of damage accumulation and the diminishing driving effect of subsequent blasts due to energy dissipation and compaction within the already-damaged zone. The study provides key theoretical and analytical tools for evaluating the long-term stability of surrounding rock with initial damage under cyclic blasting.

CO2 phase-transition blasting is a non-explosive technique that utilizes the energy released during the phase transition of carbon dioxide. The state transformation of CO2 and the fracture behavior of fracturing tubes directly determine the effectiveness of the blasting process. Inside the fracturing tube, CO2 undergoes successive stages, including pressurized filling, thermal phase transition, and jet release, during which its temperature, pressure, and phase undergo significant changes. Tubes with different structural configurations exhibit distinct failure modes under CO2 pressure. Reusable bottom-discharge tubes control the release pressure via a constant-pressure rupture disc, whose pressure-bearing capacity is governed by its size and strength, showing a pronounced linear relationship among the main influencing factors. In contrast, disposable side-discharge tubes are influenced by groove parameters, and response surface analysis reveals that groove depth, groove length, and groove width affect the tube’s ultimate internal pressure in descending order. During release, CO2 forms high-velocity jets that attenuate while propagating through the annular space between the tube and the borehole wall, subsequently colliding with the wall to generate impact pressure and induce stress waves in the surrounding rock. These processes define both the dynamic and quasi-static pressure characteristics of CO2 phase-transition blasting. The findings provide a scientific reference for optimizing the effectiveness of CO2 phase-transition blasting.

The Arbitrary Lagrangian-Eulerian (ALE) formulation is an effective approach to model structural performance under blast load with consideration of fluid-structure interaction. However, this method is highly sensitive to air domain and structural mesh sizes, leading to an increased computation time and resource for an accurate prediction of blast wave magnitude, propagation, and interaction with structure. Therefore, this paper aims to utilise the application of a 2D to 3D ALE mapping technique to design a large-scale reinforced concrete (RC) column against a close-in vehicle-borne improvised explosive device (VBIED). The analysis of the column response was conducted through a three-stage process: preloading under vertical loads, blast effect assessment on the preloaded column, and evaluation of the residual load-bearing capacity of the blast-damaged column. A 2D Arbitrary Lagrangian-Eulerian (ALE) model was initially developed and validated against the Kingery-Bulmash empirical model. From this validated model, a VBIED blast event was detonated to generate blast pressure waves within the free air domain. The 2D simulation was terminated before the blast wave fully traversed the standoff distance to the structural surface. The blast pressure waves were then mapped onto a 3D ALE model incorporating the preloaded column, where key parameters including fluid-structure interaction (FSI), strain rate-dependent material properties, equations of state (EOS), and boundary conditions were rigorously defined to ensure an accurate representation of blast-structure interaction. The blast performance of the column from the 2D to 3D mapping model, including column damage and displacement time histories, was also compared with the conventional 3D ALE model. Finally, the residual axial capacity of the damaged columns was determined by using an incremental displacement-controlled load. The structural responses of the columns demonstrated comparable behaviour in both the conventional 3D ALE model and the 2D to 3D mapping ALE approach. However, the 2D to 3D mapping method achieved a substantial reduction in computational time while utilising the same computational resources. Additionally, recommendations for efficient and accurate use of the 2D to 3D ALE mapping method for designing RC structures were presented in this paper. The findings of this study provide valuable insights for engineers and researchers in structural blast engineering, facilitating the efficient application of 2D to 3D ALE mapping techniques in the design and analysis of RC structures subjected to blast loads.

In underground engineering, rockburst caused by high ground stress pose a serious threat to the safety of personnel and equipment. Destress blasting has emerged as a promising method for mitigating rockburst risks. However, traditional analysis methods for destress blasting often overlook the physical processes involved. This paper introduces a discrete element method for destress blasting analysis that considers the dynamic evolution of explosion cracks influenced by geo-stress. In this method, three stages (i.e., opening, compressing and closing) were modeled through the dynamic evolution of stiffness of explosion cracks. Based on this method, the mechanism and influencing factors of destress blasting in the tunnel face were analyzed. The results indicated that explosion cracks induced by destress blasting can induce the release and transfer of strain energy. Based on variations in strain energy at different distances from the crushing zone, rocks outside the zone are categorized into stress relief, stress concentration, and undisturbed zones. The distributing character of strain energy implies that the spacing between destress blasting holes has a crucial influence on the destress effect: as the spacing of the destress blasting hole decreases, the effect of destress blasting can be divided into three stages (i.e., independent action stage, superposition action stage and coupling action stage), therefore, inappropriate spacing can increase rather than reduce the risk of rockburst. Furthermore, the proper arrangement of destress blasting holes can promote the preconditioning effect by eliminating the stress concentration zone. These results not only enhance understanding of tunnel face preconditioning processes but also offer insights for designing destress blasting strategies in high geo-stress conditions.

Ocular motor control (OMC) and cognitive dysfunction are common persistent sequelae in persons with mild traumatic brain injury (mTBI). Combat and training operations frequently expose military Service Members to biomechanical and blast events that render them susceptible to mTBI, and problems such as OMC disturbances and cognitive dysfunction are frequent long after injury. However, these problems can be difficult to detect, often only becoming clinically evident with physical or psychological stress. Knowledge of the relationship between OMC and cognitive dysfunction in chronic mTBI, and of clinical tools to assess this issue, is limited. Setting: Academic laboratory; Marcus Institute for Brain Health, University of Colorado; Design: 2-arm, examiner-blinded cross-sectional observational study. Participants: Military Veterans with chronic mTBI (experimental; n = 38) whose most recent mTBI was more than 3 months before enrolment, and Veterans without a history of TBI (control; n = 40); Measures: The computerized King-Devick (K-D) test assessed rapid number naming tasks; the Right Eye computerized eye tracker system measured antisaccade tasks; the Conners' Continuous Performance Test (CPT) tested aspects of selective and sustained attention and impulsivity; the FAS test measured the ability to name as many common nouns that start with "F," "A," and "S" as a method to assess phonemic verbal fluency, attention, and initiation; and the Posttraumatic Stress Disorder (PTSD) Checklist for DSM-5 (PCL-5) was used as a self-report of posttraumatic stress-related symptoms. Veterans in the experimental group had a median of 2 mTBIs, and these occurred approximately 11 years before the study. On the K-D Test, the experimental group had significantly more errors and took significantly more time (51.32 seconds) compared with the control group (43.00 seconds). Significantly greater antisaccade latencies were found in the experimental group for target only, on target distractor, and ipsilateral proximal distractor paradigms, and antisaccade error rates were significantly greater in the experimental group for the contralateral proximal distractor paradigm. Significantly greater PCL-5, and worse FAS test scores and CPT commissions and omissions scores were found in the experimental group. For the experimental group, time since most recent TBI correlated with antisaccade on target distractor error rates. Regression modeling showed that FAS test scores were a significant determinant of K-D test performance. Separate regression modeling for each of the antisaccade task paradigms indicated that group status was significantly associated with antisaccade latency scores for the ipsilateral proximal distractor paradigm. PCL-5 was a significant factor for the on target distractor paradigm, and age and cognitive function denoted by FAS test and CPT scores were significant factors contributing to error rates in multiple specified antisaccade paradigm task performances. Results support the conclusion that OMC and cognitive performance are persistent co-occurring problems in Veterans with chronic mTBI. Notably, these deficits can be detected even after as few as 2 mTBIs that occurred 11 years earlier, indicating that an OMC-cognition axis of sequelae may exist in the chronic stage of mTBI. The results also identify cognitive correlates of the OMC task paradigms, aiding in the clinical application and interpretation of these tests in chronic mTBI.

Bridges are vital components of transportation networks, supporting economic, social, and emergency response functions. Their long service lives, however, expose them to multiple hazards, including fire, impact, and blast events. Although these anthropogenic events are low in probability, their consequences can be severe, especially when cascading effects occur. This paper presents a foundational framework for estimating the risk profile of existing road bridges under such scenarios, addressing a recognised gap in current national risk management procedures. Three risk models from the literature are applied to a representative sample of 50 Italian road bridges to evaluate their capacity to capture the complexity of low-probability, high-consequence (LPHC) events. Shared risk components—hazard, exposure, and vulnerability—are analysed to identify critical gaps and areas of convergence. The study also explores the role of subjective judgments, data limitations, and methodological assumptions in shaping risk estimates. A comparative analysis reveals the variability and sensitivity of outcomes across different hazard-specific risk models. The proposed framework supports a harmonised approach to risk estimation aligned with Italy’s 2020 national bridge guidelines. Ultimately, the work aims to enhance decision-making, strengthen infrastructure resilience, and improve the integration of anthropogenic risk assessment in bridge management practices.

Deep hard rock mines worldwide increasingly face rockbursts as mining depths increase. The accumulation of stress at depth results in violent and sudden energy release, causing rockmass damage. Rockbursts present numerous challenges, including fatalities, injuries, damage to expensive mining machinery, loss of production areas, increased material handling and excavation rehabilitation costs, and broader social and economic impacts. This paper focuses on destress blasting as one of the strategies for managing rockbursts. Practical experience with destress blasting in Swedish deep hard rock mines is limited, necessitating a review of global experiences to inform best practices in Sweden. Previous studies have shown that destress blasting stabilises mining excavations by redistributing peak stress away from mining zones into the surrounding rockmass, primarily by extending fractures. Key factors for an optimal destress blasting design include stress regime, rockmass properties, blast borehole dimensions and spacing, explosive properties, initiation sequence, and mining sequence. Given the geological and geotechnical variability across and within mines, it is impractical and costly to test numerous destress blasting design permutations in actual mining conditions. Numerical simulations play a crucial role in optimising designs by evaluating stress, energy, and stiffness variations to determine the most effective parameters before field implementation. This study also presents different approaches for evaluating the effectiveness of destress blasting and highlights current research limitations, recommending future studies to refine destress blasting strategies for Swedish deep hard rock mines.

In this study, a three-dimensional nonlinear finite element (FE) model was developed using Abaqus/Explicit to simulate the effects of internal blasts. The numerical model was validated against two previously published numerical and experimental works, demonstrating strong agreement in deformation results. A parametric study was carried out to evaluate the influence of several key factors on the deformation of the receiver tunnel subjected to an explosion in the adjacent donor tunnel. The investigation considered critical variables such as lining material, tunnel inner diameter, cross-sectional shape, spacing between tunnels, and TNT charge weight. The results clearly indicate that expanded polystyrene (EPS) foam, across various densities, demonstrates superior capacity for absorbing blast waves compared to polyurethane and aluminum foams. Furthermore, it was found that lower-density EPS foam provides enhanced mitigation of deformation in tunnel linings. The findings also revealed that damage to the tunnel walls is more strongly correlated with the tunnel shape where the circular tunnel exhibited the best performance. It showed the lowest deformation and delayed peak response. In addition, tunnel deformation increases markedly with higher TNT charge weights. A blast of 1814 kg produced approximately five times the deformation compared to a 454 kg charge. Moreover, it is seen that increasing the spacing between donor and receiver tunnels from 1.5 D to 2.5 D led to a 38.7% reduction in maximum deformation.

To systematically investigate the protective effects of helmets against human head injuries under various shock wave conditions, a finite element head-helmet coupling model was developed. This model analyzed how helmets influence biomechanical response parameters, such as intracranial and cranial pressure, when subjected to a single blast wave and its accompanying shock wave. While extensive research exists on single blast scenarios, studies on the more complex and militarily relevant accompanying shock waves, which pose a greater threat due to prolonged loading and multiple reflections, remain scarce. Several impact scenarios were considered, including single frontal impact, positive continuous impacts, successive sidewall impacts, and simultaneous frontal and lateral impacts. The study examined the dynamic changes in brain tissue within a blast environment to assess the efficacy of helmets in protecting the human head. In single frontal impact scenarios, helmets effectively reduced intracranial pressures in the frontal, occipital, and parietal lobes by 32 %, 38 %, and 19 %, respectively, while significantly decreasing the stress peak at the back of the skull. During positive continuous impacts, helmets decreased intracranial pressure in the parietal and occipital lobes by 36 % and 21 %, respectively, although their effectiveness in reducing frontal lobe pressure was limited due to inadequate facial protection. For successive sidewall impacts, helmet protection delayed the blast wave, reducing intracranial pressure in the frontal lobe by 60 kPa but increasing pressure in the parietal lobe by 80 kPa. This alleviated stress on the skull’s rear while increasing stress on the opposite side. In scenarios involving simultaneous frontal and lateral impacts, lateral blasts increased parietal intracranial pressure by 20 kPa, with the right hemisphere experiencing more pressure than the left due to the mitigating effect of reflective side blasts on skull stress. The study found that, compared to single blast waves, accompanying shock waves present a greater risk of cranial injuries due to their prolonged impact. These findings address a critical gap in blast neurotrauma research and provide valuable insights into the biomechanics of head injuries under realistic multi-blast conditions, which can directly inform the design of improved helmets with enhanced protection in complex blast environments. However, because shock waves may originate from multiple directions and elevations, the protective capability of conventional helmets for the facial region remains limited.