Search Results (80)

Chemical leakage accidents in chemical industrial parks pose significant threats to personnel safety, particularly during evacuation processes, where individual behavior and evacuation strategies have a considerable impact on overall efficiency. This study takes a leakage incident at an alkylation unit as a case study. First, ALOHA5.4.7 software was used to simulate the influence of meteorological conditions across different seasons on the dispersion range of toxic gases, thereby generating an annual comprehensive risk zone distribution map. Subsequently, different evacuation scenarios were constructed in Pathfinder2024.1.0605, with the integration of trigger mechanisms to simulate individual behaviors during evacuation, such as variations in risk perception and peer influence. Furthermore, this study expanded the conventional application scope of Pathfinder—typically limited to small-scale building evacuations—by successfully adapting it for large-scale evacuation simulations in chemical industrial parks. The feasibility of such simulations was thereby demonstrated, highlighting the software’s potential. According to the simulation results, exit configuration, shelter placement, and individual behavior modeling significantly affect the total evacuation time. This study provides both theoretical insights and practical guidance for emergency response planning in chemical industrial parks. Full article

The fire resistance performance of steel beams is of utmost importance to the fire safety of building structures and personnel evacuation. To address the deviation in the assumption of uniform temperature distribution in traditional studies, this study conducted multiple simulation tests. It was found that when the size of the vent was reduced by 50%, the difference in the heating rate in the early stage of the fire was 30% to 50%. Increasing the load ratio from 0.2 to 0.8 can significantly reduce the critical temperature of the steel beam by 15% to 20%, and the corresponding critical temperature is reduced from 670 °C to 565 °C. Based on parametric analysis, a simplified evaluation model of critical temperature for Q460 high-strength steel beams is proposed. The calculation error of the model is less than 5%, which provides a theoretical basis for the whole process of fire protection design. The research achievements break through the limitations of traditional methods and offer innovative approaches to predicting the fire resistance performance of steel beams and their optimized design. Full article

This study investigates the spread patterns of tunnel fires and examines issues related to emergency response. It focuses on the temperature characteristics, spread patterns, conditions leading to multi-source fires, and the efficacy of water mist suppression methods in heavy-haul railway tunnel fires. The research employs theoretical derivations and numerical simulations to achieve its objectives. It was discovered that, during a fire in a heavy-haul railway tunnel, the temperature inside the tunnel can exceed 500 °C. Furthermore, depending on the nature of the goods transported by the train and under specific wind speed conditions, the fire source has the potential to spread to other carriages, resulting in a multi-source fire. Using the numerical simulation software Pyrosim 2022, various wind speed conditions were simulated. The results revealed that at lower wind speeds, the smoke demonstrates a reverse flow phenomenon. Concurrently, when the adjacent carriage on the leeward side of the fire is ignited, the high-temperature reverse flow smoke, along with the thermal radiation from the flames, ignites combustible materials in the adjacent carriage on the windward side of the burning carriage. Through theoretical derivation and numerical simulation, the critical wind speed for the working conditions was determined to be 2.14 m/s. It was found that while a higher wind speed can lead to a decrease in temperature, it also increases the flame deflection angle. When the wind speed exceeds 2.4 m/s, although the temperature significantly drops in a short period, the proximity of combustible materials on the leeward side of the carriage becomes a concern. At this wind speed, the flame deflection angle causes heat radiation on the leeward side, specifically between 0.5 m and 3 m, to ignite the combustible materials on the carriage surface, resulting in fire spread and multiple fire incidents. The relationship between wind speed and the angle of deflection from the fire source was determined using relevant physics principles. Additionally, the relationship between wind speed and the trajectory of water mist spraying was established. It was proposed to optimize the position of the water mist based on its deviation, and the results indicated that under critical wind speed conditions, when the water mist spraying is offset approximately 5 m towards the upwind side of the fire source, it can act more directly on the surface of the fire source. Numerical simulation results show a significant reduction in the maximum temperature and effective control of fire spread. Under critical wind speed conditions, the localized average temperature of the fire decreased by approximately 140 °C when spraying was applied, compared to the conditions without spraying, and the peak temperature decreased by about 190 °C. This modification scheme can effectively suppress the threat of fire to personnel evacuation under simulated working conditions, reflecting effective control over fires. Additionally, it provides theoretical support for the study of fire patterns in tunnels and emergency response measures. Full article

Architectural design seeks to address many challenges, one of which is creating buildings that can quickly and safely evacuate people. Therefore, it is even more important to pay attention to the safety of personnel evacuation. Past disasters have shown that the number of casualties in large sports stadiums can be as severe as those caused by plane crashes. This study uses a case study approach to analyze the evacuation of spectators in a 40,000-seat stadium, comparing the practical application of three performance verification methods. The results indicate that Simulex’s visual dynamic simulation effectively reflects how walking speeds decrease in crowded conditions and how bottlenecks form along evacuation routes. People tend to gather at corners, leading to congestion and uneven distribution of evacuees, with several escape staircases being underutilized. The Guide to Safety at Sports Grounds is suitable for the early planning stages of architectural design, while the “Verification Guideline of Buildings Evacuation Safety Performance-based Design” is better suited for the detailed design phase to ensure compliance with the safety standard of evacuating spectators within 8 min. Compared to planning and designing based solely on regulations or empirical verification formulas, using visualization software allows for effective adjustments to evacuation routes before finalizing the design, balancing crowd flow across all safety exits and improving evacuation efficiency during the operational phase. Full article

The enclosed nature of indoor building spaces during fires creates complex fire environments and restricted evacuation routes, substantially elevating the risk of mass casualties. Traditional static evacuation routes not only overlook the complexity of fire scenarios but also fail to satisfy safety requirements for evacuation. To address this issue, this study proposes an enhanced A* algorithm to determine evacuation paths based on dynamic fire risk assessment. A dynamic fire risk assessment model is established using key fire environment parameters (e.g., temperature, visibility, and toxic gas concentration) and their corresponding personnel harm thresholds. This model quantifies fire risks within a discrete space. The A* algorithm is improved by integrating fire risk values and initial direction constraints into its heuristic function and path update strategy, thereby increasing the algorithm’s accuracy and efficiency. Using a subway station fire as a case study, the simulation results indicate that the improved algorithm can update evacuation paths in line with the dynamic evolution of fire risks. It also identifies evacuation routes by balancing fire risk, distance, and initial direction. This approach maintains the original path direction while substantially reducing path risk, achieving an approximate 70% reduction in individual evacuation path risk. This method can guide building fire safety design and the formulation of emergency evacuation plans. It also serves as a reference for path guidance during emergencies. Full article

Emergency water release from underground reservoirs is characterized by its suddenness and significant harm. The quantitative prediction of water spreading processes in mine tunnels is crucial for enhancing underground safety. The study focuses on an underground roadway in a coal mine, constructing a three-dimensional physical model of the complex tunnel network to explore the spatiotemporal characteristics of water flow spreading after water release in coal mine tunnels. The Volume of Fluid (VOF) model of the Eulerian multiphase flow was adopted to simulate the flow state of water in the roadway. The results indicate that after water release from the reservoir, water flows along the tunnel network towards locations with relatively lower altitude terrain. During the initial stage of water release, sloping tunnels act as barriers to water spreading. The water level height at each point in the tunnel network generally experiences three developmental stages: rapid rise, slow increase, and stable equilibrium. The water level height in the tunnel area near the water release outlet rises sharply within a time range of 550 s; tunnels farther from the water release outlet experience a rapid rise in water level height only after 13,200 s. The final stable equilibrium water level in the tunnel depends on the location of the water release outlet and the relative height of the terrain, with a water level height ranging from 0.3 to 3.3 m. The maximum safe evacuation time for personnel within a radius of 300 m from the drainage outlet is only 1 h. In contrast, areas farther away from the drainage location benefit from the water storage capacity of the complex tunnel network and have significantly extended evacuation opportunities. Full article

Floods resulting from dam failures are highly destructive, characterized by intense impact forces, widespread inundation, and rapid flow velocities, all of which pose significant threats to public safety and social stability in downstream regions. To improve evacuation efficiency during such emergencies, it is essential to study flood evacuation route planning. This study aimed to minimize evacuation time and reduce risks to personnel by considering the dynamic evolution of dam-break floods. Using aerial photography from an unmanned aerial vehicle, the downstream road network of a reservoir was mapped. A coupled flood–road network coupling model was then developed by integrating flood propagation data with road network information. This model optimized evacuation route planning by combining the dynamic evolution of flood hazards with real-time road network data. Based on this model, a flood evacuation route planning method was proposed using Dijkstra’s algorithm. This methodology was validated through a case study of the Shanmei Reservoir in Fujian, China. The results demonstrated that the maximum flood level reached 18.65 m near Xiatou Village, and the highest flow velocity was 22.18 m/s near the Shanmei Reservoir. Furthermore, evacuation plans were developed for eight affected locations downstream of the Shanmei Reservoir, with a total of 13 evacuation routes. These strategies and routes resulted in a significant reduction in evacuation time and minimized the risks to evacuees. The life-loss risk was minimized in the evacuation process, and all evacuees were able to reach safe locations. These findings confirmed that the proposed method, which integrated flood dynamics with road network information, ensured the safety and effectiveness of evacuation routes. This approach met the critical needs of emergency management by providing timely and secure evacuation paths in the event of dam failure. Full article

To address the significant problems of high fire risk and low evacuation efficiency in large and complex medical buildings, this study uses Ezhou Hospital as the empirical object to construct a multi-dimensional threat and risk assessment and fire evacuation dynamic coupling model and proposes a systematic optimization scheme to improve personnel evacuation safety. This study proposes an innovative full-chain analysis framework of “threat and risk assessment-dynamic coupling-multi-strategy optimization”. The specific methods employed include the following: (1) Using the probabilistic threat and risk assessment (PRA) method and the risk index (RII) method to identify the most unfavorable scenarios where the fire source is located in the outpatient hall (risk value C2 = 9.86). (2) Combining PyroSim and Pathfinder to construct a dynamic coupling model of fire smoke diffusion and personnel evacuation. Multiple groups, such as patients with mobility problems and rescue personnel, are added to address the limitations of traditional single-factor simulations. (3) Considering the failure of fire shutters, a two-stage optimization strategy is proposed for when the number of personnel is at its peak: the evacuation time is shortened by 23% by using internal intelligent guidance to shunt the congestion node crowd, and the addition of external fire ladders forms a multi-channel coordinated evacuation that further reduces the total evacuation time from 1780 s to 1266 s and improves the efficiency by 29%. The results show that the coupled multi-path coordination strategy and three-dimensional rescue facilities can significantly reduce the bottleneck associated with a single channel. This study provides a multi-dimensional dynamic evaluation framework and comprehensive optimization paradigm for the design of the evacuation of high-rise medical buildings and has important theoretical and technical reference values for improving the fire safety performance of public buildings and the intelligence of emergency management. Full article

The rapid pace of global urbanization has exacerbated the urban wind-heat environment, posing a severe threat to public health and sustainable urban development. This study explores the aerodynamic transport characteristics of bioaerosols in a local urban area of Beijing following an accidental bioaerosol release. By coupling the Weather Research and Forecasting (WRF) model with a Computational Fluid Dynamics (CFD) model, the research accounts for the temporality of urban airflow and atmospheric stability. A dose–response model was employed to assess the exposure risks to Beijing Institute of Technology personnel. The findings reveal substantial differences in flow fields and bioaerosol dispersion under varying atmospheric stability: the infection area ratio was 42.19% under unstable conditions and 37.5% under stable conditions. Infection risk was highest near the release source, decreasing with distance. Under the three stability conditions, the probability of infection is highest near the release source and decreases with increasing distance. Contaminants propagate more rapidly under unstable conditions, while stable conditions have a higher concentration of high-risk areas. Gender-based analysis indicated a higher infection probability for males due to elevated inhalation rates. This study elucidates the critical role of atmospheric stability in bioaerosol dispersion and provides a robust scientific foundation for biosafety planning, including early warning, mitigation, and emergency evacuation strategies. Full article

Due to the complexity of the architectural structure within comprehensive teaching buildings and the diversity of the student population, these buildings face more intricate fire safety challenges than ordinary teaching buildings. Current research primarily focuses on the analysis of single-building structures or individual factors, lacking an examination of the mechanism of multiple factors on emergency evacuation. Therefore, this study takes a comprehensive teaching building with a complex structure as a case study and, considering the behavioral characteristics of university personnel, conducts simulations using Pathfinder software. The model evaluates the effectiveness of pedestrian flow, vertical personnel distribution, horizontal functional zoning, priority ranking adjustments, and combination strategies on evacuation, as well as the impact of psychological factors on evacuation efficiency, providing a comparative analysis of the influence of each factor on evacuation. The results indicate that controlling the number of people in classrooms at the same time to reduce pedestrian flow can effectively shorten evacuation time, improving evacuation efficiency by 17.63%. The reasonable optimization of functional zoning and priority ranking can also effectively reduce evacuation time. In cases where there is high personnel density on upper floors and the teaching building’s functional zoning is unreasonable, the optimization effect of combination strategies is particularly significant, improving evacuation efficiency by 23.94%. Under panic conditions, leaders can effectively improve evacuation efficiency, and their role becomes increasingly significant as the level of panic rises. By considering the impact of various factors on evacuation, this research aims to enhance the evacuation efficiency of teaching buildings. The findings provide a scientific basis for emergency evacuation in complex buildings like teaching facilities. Full article

In order to investigate the influence of factors such as pheromones and avoidance behavior on the evacuation of heterogeneous crowds, a multi-speed cellular automata evacuation model based on asymmetric competitiveness is proposed for the evacuation of the complex groups in a single-exit room. By optimizing the crowd density and pedestrian speed equations, multi-speed heterogeneous crowds can be obtained in the model. In order to achieve the description of a multi-dimensional asymmetric competitiveness heterogeneous population, the evacuation competitiveness is considered in the pedestrians with different speed, age, gender, etc., and by considering the avoidance character existing among pedestrians, the avoidance behavior is also discussed in this model. It is well known that the information received by different pedestrians is different. In order to consider the asymmetry of information, the pheromones are introduced into the evacuation model to discuss the effect of information differences on evacuation. The evacuation results show that the asymmetry of information has a facilitating effect on the evacuation speed of pedestrians, and the best evacuation effect is obtained when the radius of the pheromone is about 3 m. Moreover, evacuation time is weakly correlated with pedestrians’ gender but strongly correlated with pedestrians’ age. The avoidance behavior plays a positive role in evacuation, and the evacuation time reaches the minimum value when the avoidance probability is about 0.5. The slope of the reduction in evacuation time is greatest when the avoidance threshold is 0.4 to 0.8. The findings can support evacuation capacity assessment, emergency planning, and decision making. Full article

To investigate public perceptions regarding tunnel fire disasters and optimize the tunnel fire disaster prevention framework, this study takes the emerging social media platform Douyin as a case study, conducting an in-depth analysis of 2133 short videos related to tunnel fires on the platform. A computational communication method was used for analysis, Latent Dirichlet Allocation was used to cluster the discussion topics of these tunnel fire short videos, and a spatiotemporal evolution analysis of the number of videos posted, user comments, and emotional inclinations across different topics was performed. The findings reveal that there is a noticeable divergence in public opinion regarding emergency decision making in tunnel fires, related to the complexity of tunnel fire incidents, ethical dilemmas in tunnel fire escape scenarios, and insufficient knowledge popularization of fire safety practices. The study elucidates the public’s actual needs during tunnel fire incidents, and a dynamic disaster prevention framework for tunnel fires based on social media and artificial intelligence is proposed on this basis to enhance emergency response capabilities. Utilizing short videos on social media, the study constructs a critical target dataset under real tunnel fire scenarios. It proposes a computer vision-based model for identifying critical targets in tunnel fires. This model can accurately and in real-time identify key targets such as fires, smoke, vehicles, emergency exits, and people in real tunnel fire environments, achieving an average detection precision of 77.3%. This research bridges the cognitive differences between the general public and professionally knowledgeable tunnel engineers regarding tunnel fire evacuation, guiding tunnel fire emergency responses and personnel evacuation. Full article

In view of the spread and distribution of high-temperature toxic smoke on the working face during belt conveyor fires, the FDS was used to carry out numerical simulation, establish a belt conveyor fire simulation model, set up a variety of working conditions, and study the flue gas spread of the working face with different ignition source locations and different heat release rates. The results show that the flue gas reaching the working face varies greatly from different ignition source locations, and the smoke propagation time of the working face decreases first and then increases with the increase in the scale of the fire. The location of the fire source is from 0 to 700 m, and the visibility of the working face will drop to less than 3 m within 10 min, which seriously affects emergency evacuation; the maximum concentration of CO in the working face is proportional to the heat release rate, the fire source is less than 100 m away from the working face, and the temperature of the air inlet area of the working face is higher than 60 °C, which poses a great threat to personnel evacuation. When the fire source is less than 200 m away from the working face, the evacuees will encounter smoke damage on the working face, and when the fire scale reaches 4 MW and 6 MW, the CO concentration will have a great impact on the evacuation and make people incapacitated. Full article

In case of emergency, evacuation signs play an important role in guiding people to evacuate safety exits in large space buildings. Large space buildings are characterized by high ceilings and large areas. In the existing legislation and standards, the height setting of evacuation signs is fixed, but the influence of height changes on the visibility of evacuation signs is very important. This study fully considers the relationship between the height setting change of evacuation signs and the visual range and puts forward a smart safety design strategy for evacuation signs. The smart safety design consists of two parts, one is the mathematical relationship between the height change of evacuation signs and the visual range of personnel, and the other is the integration of the application process of smart devices. Firstly, the visual range of two different sizes of evacuation signs placed at the height of 1.7 to 6 m was measured experimentally in China. The results showed that: (1) with an increase in the height of the evacuation signs, their viewing distance gradually decreased and the visual range was reduced; (2) the mathematical model of the change between the height and the visual range of evacuation signs was established; (3) the height of evacuation signs between 3 to 5 m agreed more with the visual habits of the people. Then, on this basis, the smart safety design method can use related mathematical models to set the evacuation signs at the optimal height based on the actual distance between people and evacuation signs, ensuring that people can see the signs the first time, thus providing evacuation guidance for evacuees and improving the safety of large space buildings. Full article

Existing research into this topic primarily focuses on low-altitude areas, neglecting the impact of extreme environmental conditions such as low temperature, low oxygen level, and low pressure in high-altitude regions. Based on the smoke diffusion theory, a series of CFD numerical simulations were conducted in order to investigate the characteristics of smoke diffusion in the highway tunnel at high altitude. The results indicated that the increase in altitude would enhance the longitudinal propagation velocity of smoke, leading to a more pronounced impact on temperature, CO concentration, and visibility at characteristic heights. Meanwhile, the altitude intensifies the inhibitory impact of longitudinal ventilation on smoke diffusion upwind of the fire source and augments the acceleration effect on smoke diffusion downwind, thereby impeding personnel evacuation on the downwind side. By taking the hazardous range at a characteristic height under the impact of wind velocity and the deceleration of evacuation velocity due to altitude into consideration, a new recommended reduction factor was deduced to design adits for people passing spacing in highway tunnels at high altitude. The findings can serve as a valuable reference for the personal evacuation in high-altitude highway tunnel fires and the design of spacing between adits for people passing within such tunnels. Full article