Personnel Escape Research Articles

Study of spatial temperature features of road tunnel fires under multiple factors

AbstractAfter a highway tunnel fire, the rapid change of the internal ambient temperature directly affects the personal safety of pedestrians. Based mainly on the lateral possibility of fire location and considering the coupling effect of multiple factors in a two‐lane highway tunnel, this study systematically carried out 63 full‐size tunnel fire simulation studies relying on Fluent software. The smoke temperature distribution patterns in the transverse and longitudinal spaces of the tunnel after the fire were revealed. This study shows that the smoke temperature below the tunnel vault is susceptible to the effect of sidewall restraint, making the maximum temperature of the tunnel vault of the offset fire source large; considering the lateral location of the fire source, the maximum temperature prediction formula of the tunnel vault is modified to expose the change law of the longitudinal temperature decay of the vault. This paper reveals for the first time the law of temperature distribution changes at the characteristic height of the human eye on the evacuation platform in the tunnel; the systematic study of the fire source cross‐sectional temperature distribution changes at the key lining structure points, and it is found that a low‐temperature space conducive to personnel escape exists in the lower part of the tunnel away from the fire source side. The results of the study are beneficial to the design of safe evacuation paths in the tunnel and the active emergency evacuation of personnel in the near‐fire source area.

Pyrolysis and combustion characteristics of typical sealing materials for exterior building windows

Seals play a crucial role in preventing flame penetration through building exterior windows. However, as urban renewal accelerates, the number of discarded seals is also gradually increasing, which is not in line with the concept of green, energy-saving sustainable development. To gain a better understanding of the pyrolysis and combustion characteristics of sealing strips and facilitate their effective resource utilization and conversion into value-added fuels, we employed thermogravimetry, cone calorimetry, and flue gas spreading test equipment. Typical sealing and filling materials used for external windows of buildings, including EPDM ordinary adhesive strips (EPDM-O), EPDM flame-retardant adhesive strips (EPDM-R), as well as 20-fold expanding graphite strips and 30-fold expanding graphite strips (EG-20 and EG-30), were investigated. Comprehensive evaluations of their pyrolysis behaviors, kinetic parameters, and combustion characteristic parameters were carried out. The results showed that EPDM exhibits good thermal stability, while EG had better demonstrates favorable pyrolysis properties and expansion densification. Average activation energies of EPDM-O and EPDM-R in the combustion phase were 68.35 kJmol−1 and 92.40 kJmol−1, respectively. Moreover, the average activation energies of EG-20 and EG-30 in the expanding combustion phase were 67.42 kJ·mol−1 and 68.62 kJ·mol−1, respectively. The reaction rate of combustion stage is faster than that of pyrolysis stage. Furthermore, For the combustion, the flame growth index (FGI) of EPDM is greater than that of EG, whereas the flame spread index (FPI) is lower than EG. When EPDM burns, the flame spreads rapidly, while EG expands and generates a large number of wormlike substances, effectively preventing the high temperature from spreading to the interior of the material. Analyses of smoke spreading tests have shown that both EPDM and EG can produce irritating flammable fumes at high temperatures, affecting the environment. These results provide a basis for the development of new materials and contributes to fire safety, smoke management, and personnel escape planning.

Fire Protection and Evacuation Analysis in Underground Interchange Tunnels by Integrating BIM and Numerical Simulation

Rescue and evacuation of underground interchange tunnels after a fire are challenging. Therefore, a method of integrating building information modeling (BIM) and a fire dynamic simulator (FDS) was proposed to analyze fire characteristics and personnel escapes in underground interchange tunnels. A BIM model of underground interchange tunnels was built, and then different formats (DXF and CAD) were generated and imported into Pyrosim software and Pathfinder software. With an increase in ventilation velocity, the CO concentration and temperature downstream of the fire source increased, and visibility decreased, according to simulation results. The critical ventilation velocity was 3.6 m/s at 30 MW. Evacuation simulation results suggested that the congestion of the transverse passage was very unfavorable for personnel escape: the escape time increased by 14.9% and 20% when the interior and entrance of the transverse passage were severely congested, while a 2.5 m wide transverse passage effectively reduced the escape time. Visibility was the first indicator that it did not meet the safety of the escape. After the tunnel’s personnel have been evacuated, the air supply or exhaust system should be started, and smoke should be expelled at a higher velocity. It is necessary to clear the passageway quickly or increase the automatic firefighting facilities when congestion is severe.

Investigation on the concentration prediction model and personnel hazard range of LNG leakage from tankers in the tunnel

Liquid natural gas (LNG) leaks from tanker in the tunnel could result in more severe fire and explosion catastrophes than those that occur in unconfined space. Investigating the gas concentration distribution law and the accompanying personnel hazard range is crucial to provide guidelines for personnel escape and fire rescue in such accidents. In this paper, to provide a rapid technique for concentration estimation, the virtual source approach and the fluid settlement theory are applied to put forward a new model, which is based on the Gaussian plume model. Three batches of LNG diffusion tests were carried out in a 5 m long wind tunnel with a cross-section of 1 m × 1 m. The comparison results show that the prediction accuracy of the proposed model in the far region of the leakage source is better than that in the near region, with the error within ±16%, which demonstrated an accurate prediction performance of the proposed model. The numerical model of LNG leakage from tanker in the tunnel is established, and the influence of leakage direction, leakage aperture, and tunnel cross-section on concentration distribution law is discussed. The findings indicate that when the leakage direction changes from horizontal to vertical, the gas is more likely to accumulate in the tunnel due to the greater attenuation of the initial momentum of the gas, which causes the combustible range to increase by about 2 times. When the leakage aperture is 50 mm, the mass of combustible gas reaches the maximum value of 320.91 kg in 85.9 s, which indicates that the explosion intensity is not proportional to the leakage aperture. Excessive leakage aperture causes the concentration to surpass the Upper Flammable Limit, and the similar trends occur when the tunnel cross-section reduces. Based on the numerical results, the calculation model of the personnel hazard range suitable for various tunnel cross-sections and leakage apertures is derived by data fitting.

Supramolecular engineered ultrathin MXene towards fire safe polylactic acid composites

The combustion of polymeric materials will generate a mass of heat and release poisonous fumes, which not only hinders the personnel escape and causes casualties, but also causes the environmental contamination. Herein, a novel N–P–Co-containing supramolecular assembly network (MHCSN) flame retardant was synthesized by electrostatic interaction and supramolecular self-assembly technology. Then, MHCSN-Ti3C2Tx (MHCSN-TC) hybrids were synthesized by hydrogen bonding induced assembly and compounded with silicone wrapped ammonium polyphosphate (SiAPP) to successfully fabricate polylactic acid (PLA)/MHCSN-TC/SiAPP composites. PLA/MHCSN-TC/SiAPP composites exhibited the improved flame retardancy. For example, the introduction of 1.0 wt% MHCSN-TC and 14.0 wt% SiAPP into PLA resulted in significant reduction in the total heat release (50.1%), peak of heat release rate (64.1%) and peak of smoke production rate (61.3%). The improvements in flame retardance and smoke suppression of the PLA composites were due to the catalytic carbonization and barrier effect of the modified Ti3C2Tx nanoflakes. Meanwhile, the generated phosphorus-containing radicals generated by SiAPP captured the H• and HO• produced from the PLA material, and these phosphorus-containing species evolved into compact expanded char layers. This work offers a simple method to prepare highly effective flame retardants for PLA.

Emergency medical services professional behaviors with violent encounters: A prospective study using standardized simulated scenarios.

IntroductionTo evaluate emergency medical services (EMS) professional response to escalating threats of violence during simulated patient encounters and describe differences in behaviors by characteristics.MethodsEMS professionals of a large county‐based system participated in 1 of 4 standardized patient care scenarios. Each 8‐minute scenario included escalated threats of violence such that EMS personnel should escape the scene for safety. Trained evaluators recorded EMS professionals' performance using standardized data elements. Outcomes included EMS personnel escape and verbal de‐escalation attempts. Descriptive statistics and univariable odds ratios (OR) with 95% confidence intervals (95% CI) are reported.ResultsThere were 270 EMS professionals evaluated as individual members of 2‐person crews. Overall, 54% escaped the unsafe scene and 54% made an adequate de‐escalation attempt; 20% did not make an adequate de‐escalation attempt nor escape the unsafe scene. Paramedics demonstrated lower odds of escaping compared to emergency medical technicians (OR: 0.40; 95% CI: 0.17–0.94), yet greater odds of adequate de‐escalation (OR: 3.17, 95% CI: 1.38–7.31). EMS professionals with more than 20 years of experience (OR: 0.32, 95% CI: 0.13–0.79, ref:2 years or less) and those with military experience (OR: 0.37; 95% CI: 0.17–0.81) demonstrated reduced odds of escaping. Crisis intervention team (CIT) training was associated with reduced odds of escape (OR: 0.38; 95% CI: 0.21–0.69), but increased odds of adequate de‐escalation (OR: 2.19; 95% CI: 1.19–4.04).ConclusionsNearly half of EMS professionals did not remove themselves from a simulated patient care scenario with an escalating threat of physical violence. EMS‐specific training for de‐escalation as a first‐line technique, recognizing imminent violence, and leaving a dangerous environment is needed.

Parametric optimization of a novel air supply device used in tunnel fire

Tunnel widely exists in highway, subway and other underground buildings. Due to the structural limitations, the direction of evacuation is consistent with the main flow direction of smoke in the tunnel. For the design of smoke exhaust system, traditional methods aim at reducing the overall smoke concentration in the whole tunnel. However, when fire hazard occurs, rapid personnel escape requires higher visibility. In this paper, a novel air supply device designed for smoke-insulation passageway establishment and ventilation in tunnel fire is introduced. Wall-attached jet and orifice plate jet are combined in this device, which enables passageway to isolate smoke intrusion. In this study, an approach has been devised combining Response Surface Method (RSM) with numerical simulations as well as visualization experiment to get better performance of the device. Parametric optimization was conducted for the three influencing variables, i.e., the air supply volume, opening rate of orifice plate, and width of wall-attached jet. Analysis of variance (ANOVA) indicates that all the three factors are significant. Moreover, the optimal combination can be obtained within the admissible range of the three factors through response optimization. A regression equation is developed to predict the effect of the novel air supply device for any input values of the three influencing variables.

The design of energy-saving intelligent escape clothes hanger device

Due to the rapid development of economy and technology, floor molding of modern building are different, interior and exterior circuit design are more complex. Therefore, the fire also increases sharply, causing huge losses to the national economy and people’s life safety. The survival rate of personnel in serious fires has become the focus of the whole society. We take the clothes hanger as the research object in the paper, refit the clothes hanger, and provides an intelligent escape device to speed up the escape time. The device mainly includes Single-Chip Microprocessor control module, communication module, detection module, alarm module and solar panel module. The device has simple structure and convenient installation, which solves the timeliness of personnel escape in the fire and avoids secondary casualties in the fire.

Spread and burning characteristics of continuous spill fires in a tunnel

Changing burning area of spill fire may cause chain effects and expand consequences in tunnels, which poses a greater challenge to personnel escape and rescue. Research on tunnel spill fire is needed to reveal its behavior and internal mechanisms. This paper carried out a series of continuous spill fires on fireproof glass both in tunnel environment (TE) and open environment (OE). The spread, burning, and heat transfer characteristics were compared between these two environments. The results showed that spread areas of TE spill fires in quasi-steady stage were smaller than those of OE. The burning rate enhancement coefficients ranged from 0.92 to 1.76 from small spill fires and larger ones in tunnel. With respect to penetrating heat radiation and heat conduction loss, TE spill fires were slightly larger than OE spill fires. And it was proved that the heat feedback is the main cause for the burning rate enhancement in tunnel. Then a semi-empirical model was proposed by coupling the spread, burning and heat transfer process. The model was proved to be quite accurate by validating with experimental data.

Experimental investigation of burning behavior of a running vehicle

In recent years, automobile fire accidents have occurred frequently. To effectively understand the characteristics of car fire accidents, the burning behaviors of a running sedan vehicle and the fire spread characteristics were studied in this study. The spread progress of automobile fire was recorded by cameras installed in the front, side and inside of the car. The surface temperature and interior temperature of the car were measured by the infrared thermal imager and thermocouples. The engine compartment burned quickly after the fire, and smoke entered the car through the air-conditioning vents. The cab reached flashover after 10 min, and the temperature was over 1000 °C. The plastic materials of the car engine compartment were dripping in flames and the car tires were ignited by flaming droplet after 5 min. The experiment shows that in the case of engine compartment fire, personnel escape and firefighting should be performed within 6 min.

AHP and Casualties Calculation Based Research on Road Tunnel Fire Risk Evaluation

On the basis of classic risk theories this paper proposes a more pertinent and practical fire evaluation model for road tunnels. According to causes for tunnel fire, an index system for assessment of tunnel fire probability and rating criteria are established based on tunnel properties, environmental conditions, traffic status and vehicle performance. By fine modelling of tunnel fire smoke spread and personnel escape behaviour, a calculation method and rating criteria for consequences of tunnel fire are established. The research results suggest this method is a feasible means to assess road tunnel fire risks.

Study on Combustion Characteristics and Evacuation during Intake Airway Fire in Coal Face under Different Ventilation Conditions

ABSTRACT The exogenous fire is one of the major disasters of mines. It is difficult to put them out but easy to result in serious casualties and property losses. Until now, the fire combustion in mines and smoke flow characteristics under multi-factor coupling effect of wind speed, wind direction, fire source and so on are still not clear. Moreover, the interaction mechanism between fire and people escape has still not been revealed. In order to solve the above problems, this paper used the FDS numerical simulation method to study the parameter values of working face temperature and visibility of laneway as the fire occurs as well as their changes, so as to obtain the influences of fire source position and fire power on the smoke spread rate of fire in the laneway. Then, the function expressions of smoke spread rate related to the fire source position and fire power were derived, respectively, and the rationality of theoretical prediction model of longitudinal attenuation of smoke temperature was verified. Furthermore, the fire characteristic parameters and their change rules under the inverted ventilation were studied, and the optimal scheme of wind control was obtained. The results showed that the increase of inverted ventilation speed could accelerate the discharge of smoke flow from the laneway. Moreover, when the inverted ventilation speed was between 2.2 m/s and 2.7 m/s, there was an optimal wind rate for smoke discharge, which could provide relatively safe conditions for evacuation. In addition, when the power of the fire source was 10 MW, the critical wind speed to prevent the smoke flow reversal was 1.6 m/s under the condition of local inverted ventilation. Finally, this study simulated the personnel escape behavior in combination with Pathfinder to build the prediction models of evacuation time and evacuation speed in the laneway and working face. Simultaneously, the necessary time for personnel escape was analyzed, which provided a basis for the safe evacuation of personnel in the case of fire.

Escape route optimization by cellular automata based on the multiple factors during the coal mine disasters

When disaster occurs in coal mines, the complex network structure of roadways and the disaster evolution process usually cause serious casualties. An efficient escape plan becomes an important method to guarantee survivors. The factors affecting the miners’ escape during the disaster were analyzed. An experimental model was established based on the key factors such as the slope, the convex–concave degree, and the speed of the airflow. The equations between the key factors and the escape speed were fitted by a large number of experimental values. A quantitative model of high temperature, CO, CO2, and O2 concentrations, visibility, and other environmental factors related to the dynamic health of the miners was set up. A cellular automata model for the shortest route selection in the complex ventilation network was established. In order to solve this problem, we established a physical model of the ventilation system in the Tang Shan-gou coal mine. The static difficulty degree of the roadways in the complex network was calculated by classification and segmentation. The parameters such as temperature and the components of the fire smoke in the roadways were simulated by the fire dynamics simulator. The cellular automata model was improved, the static difficulty was set as the primary selection factor, and the dynamic healthy degree was set as the secondary factor. From the simulated disaster drills carried out by the miners and the numerical simulation results, we proved that it is reasonable and feasible to use the improved cellular automata model for the personnel escape route optimization.

Новые подходы в оценке пожарной безопасности персонала при его эвакуации из производственных помещений в случае возникновения пожара

In this paper have been presented new approaches to fire safety assessment of personnel during its evacuation from industrial premises. A method for composition of scenarios for a fire break-out and development based on the Ishikawa Diagram, as well as a mathematical model characterizing the process of fire break-out and development have been implemented. A fire safety index for personnel escape routes has been introduced, and models for assessment the probability of personnel evacuation have been used. Have been concerned problematic issues related to humans’ behavioral feature during fire, their moving in case of evacuation inside enclosed and confined spaces, distance of workplaces from escape routes, reliability of emergency voice alarm communication system. An approach for safety assessment of automatic fire extinguishing units containing fire-extinguishing agents which are hazardous to human health has been proposed. Examples for approbation of developments in the process of fire safety assessment for escape routes, and composition of fire in a machinery room of gas transmission provider’s compressor section have been presented.

Fire Model Test on Temperature Field in the Rescue Station of an Extralong Railway Tunnel

A rescue station is necessary for an extralong railway tunnel, whose length is generally greater than 20 km. In the rescue station, passenger evacuation, fire fighting, and protection of passengers are organized. It is important to discover the temperature distribution in a rescue station where a train is on fire. This paper performs a similarity simulation model test at 1 : 10 geometric scale to investigate the temperature field in a rescue station. A gasoline pool fire was used as the fire source. The influences of the fire source position and ventilation condition on the temperature field were studied. The results show that (a) the temperature distribution along the tunnel is stable without ventilation, the temperature is lowest when the fire occurs 50 m from the entrance; (b) the fresh air stirred up by fans promotes burning and increases the temperature; (c) the chimney effect causes the temperature field to skew in an uphill direction; (d) the opening of both fans in the adit makes the high‐temperature zone to connect through; and (e) the temperature increase at the rescue station can be divided into four stages, and the response of different fire source positions to the opening of fans is not consistent. These findings provide a basis for personnel escape design and a foundation for further study of temperature distribution in a tunnel with a rescue station.

Numerical simulation of dormitory building fire and personnel escape based on Pyrosim and Pathfinder

To analyze the fire risk in dormitory buildings, one dormitory of a university was taken as the subject to build a model using Pyrosim. This paper has analyzed the temperature, visibility, smoke layer height, heat flow, and smoke movement with all windows and doors opened and compared these with conditions when the fire origin room had closed windows. The results show that, with all windows opened, the highest temperature area is the fire origin room and the fire floor temperature is higher than the other floors. The closer to the fire source, the lower the visibility. With window closed, the fire origin room temperature and heat flow are much higher than with window open while the smoke layer height is much lower. Horizontal corridors and stairs are more seriously influenced by the smoke. When all windows are opened, rooms above are more seriously influenced by the smoke. Pathfinder simulation results show that the best time to escape is within 164.8s. In order not to affect the safety of personnel evacuation, the width of exit doors should be no less than 3 m and stair width should be no less than 1.75 m.

Numerical simulation and measurement of fire ventilation in river-crossing tunnel

This paper takes the subway train head fire in the upstream section of the river-crossing tunnel as the research object. The ventilation velocity with different patterns was simulated by STESS software. Then the influence of ventilation velocity on the distribution, temperature and visibility of smoke in running tunnel was studied by non-premixed combustion model in CFD software. And the ventilation velocity of recommended pattern was measured and verified. The results show that the opening and closing of the screen door in the direction of personnel escape has a great influence on the ventilation velocity of the tunnel. When the screen door is opened, it is recommended to open the 6 TVF fans in the running tunnel and the two stations. This can effectively inhibit the smoke return and meet standardized requirements.

Information fusion of plume control and personnel escape during the emergency rescue of external-caused fire in a coal mine

After a fire occurred in a coal mine, compared with putting out the fire, organizing the miners’ safe escape was especially important. We established a local ventilation system model using TEPS (Thunderhead Engineering PyroSim) and set up control measures for fire smoke. The change rule of fire parameters, such as temperature, concentration of smoke, and visibility, was analyzed based on the results of FDS (Fire Dynamics Simulator). Without the control measures for fire smoke, the coal face and the intake airflow roadway were all polluted by smoke at 541 s after the fire broke out; at this time, personnel escape would be almost impossible in the coal face. Thus, the personnel escape conditions and routes are determined by the parameters of fire smoke flow. Evac was used to simulate the escape behavior of a miner who encounters an accident in a coal mine. After taking the fire smoke control measures into account, we performed simulation calculation to determine the best and fastest way for miners’ escape. We exploited the hardware and software, and the belt fire emergency rescue system of the No. 1 plate in the Da Liu-ta coal mine was established. The emergency rescue system successfully fused fire plume control and personnel escape information into one platform. Through simulating a fire drill three times, the air quantity of the key branches changed to within reasonable limits while the air-door's opening area was 2m2, field tests proved the reliability and feasibility of the system.

Intelligent Ventilation and Emergency Evacuation of Underwater Tunnel under fire Conditions

With the development of traffic cause, the number of underwater tunnel increased year by year. The tunnel fire accidents at home and abroad in recent years have caused a large number of casualties and property losses. The layout form of underwater tunnel is special, in the event of fire, the consequence will be unimaginable. The study of ventilating control and fire evacuation of underwater tunnel is urgent and necessary. Propose the Fuzzy PID ventilation algorithm and intelligent control mode of emergency evacuation signs from the perspective of keeping wind speed zero around fire point and induction of personnel escape. Write the PLC program and simulate the emergency evacuation signs’ automatic control under the condition of tunnel fire.

Dynamic numerical simulation of coal mine fire for escape capsule installation

Fire in mine laneway leads to disordered ventilation system airflow, and smoke will result in staff poisoning. In such situation, it necessitates to install a rescue capsule in the common staff area. In this paper, the software Fluent was used to simulate the airflow conditions dynamically in No. 5 belt roadway of Kongzhuang Coal Mine when fire broke out. The migration law of CO front was determined. By underground escape experiments, personnel escape velocity model in pathway was established. Based on the numerical simulation and results of field experiments, the escape capsule installation location in the passageway of No. 5 belt roadway was ascertained.