The results from a number of investigations and fire experiments are presented and analyzed in order to characterize the fire behavior of mining vehicles in underground hard rock mines. The analysis also includes fire...The results from a number of investigations and fire experiments are presented and analyzed in order to characterize the fire behavior of mining vehicles in underground hard rock mines. The analysis also includes fire safety and fire protection measures with respect to the mining vehicle fire behavior.Earlier studies on fires in underground hard rock mines have shown that vehicles or mobile equipment are the dominant sources of fire. A better knowledge about the fire behavior of vehicles in underground hard rock mines is therefore needed. During the analysis the direction and flow rate of the ventilation in a drift was found to have a significant impact on the fire behavior, causing for example flame tilt with rapid fire spread. The shielded sections of a vehicle will be less affected by the ventilation flow resulting in for example a decreased flame spread. It was also found that spray fires may result in considerable heat release rate but are generally of shorter duration and will not make any significant contributions to the overall heat release rate of the fully developed vehicle fire. The fire duration of a loader tire from a full-scale fire experiment was found to be at least 200 min and will largely determine the total fire duration of the vehicle. A different scenario with different conditions with for example a slower flame spread resulted in an even longer fire duration. The radiative and convective fraction will be a key factor when determining the heat transfer mechanisms involved in a fire and will vary from material to material.Calculations show that the radiative fraction of the tire fires on two mining vehicles is significantly lower than found in earlier experiments. The design and construction of the mining vehicle will have an important impact on the fire behavior and could possibly mitigate the consequences of a fire and allow fire personnel to extinguish a fire that otherwise would have had a too high heat release rate.展开更多
In this study, a series of flame-retardant polyisocyanurate-polyurethane (PIR-PUR) foams were prepared using various concentrations (0-25% by weight) of expandable graphite (EG) and dimethyl methyl phosphonate (DMMP) ...In this study, a series of flame-retardant polyisocyanurate-polyurethane (PIR-PUR) foams were prepared using various concentrations (0-25% by weight) of expandable graphite (EG) and dimethyl methyl phosphonate (DMMP) (0-7% by weight). The effect of these additives on the properties of the PIR-PUR foams, including physico-mechanical, morphological, flame retardancy, and thermal stability, was studied. Increasing amounts of EG in the PIR-PUR foam caused a significant drop in the compression strength. However, DMMP caused the mechanical properties of PIR-PUR foam to improve compared to foam filled with EG alone. The flame retardancy of PIR-PUR foams containing both EG and DMMP was enhanced significantly compared to EG filled foams. Thermogravimetric analysis (TGA) indicated that EG enhances the thermal stability of PIR-PUR foams but that DMMP decreased it. The morphology of the residual char provided conclusive evidence for the weak thermal stability of foams filled with DMMP.展开更多
To investigate the temperature field and residual bearing capacity of the sandwich wall panels with GFRP skins and a wood-web core under a fire,three sandwich walls were tested.One of them was used for static load tes...To investigate the temperature field and residual bearing capacity of the sandwich wall panels with GFRP skins and a wood-web core under a fire,three sandwich walls were tested.One of them was used for static load test and the other two for the one-side fire tests.Besides,temperature probe points were set on the sandwich walls to obtain the temperature distribution.Meanwhile,the model of the sandwich wall was established in the finite element software by the method of core material stiffness equivalent.The temperature distribution and performance reduction of materials were also considered.The residual bearing capacity of specimens after fire exposure were simulated considering the effects of web spacing,wall panel thickness and fire exposure time.Because the sandwich wall panels were stressed by eccentric compression after a fire,the residual compressive strength of the wall panel after the fire can be calculated through the eccentric loading analysis.Compared with the numerical results,it can be concluded that the effectiveness of calculation method of residual bearing capacity after fire exposure was proved.展开更多
This paper presents an overview on fire behavior of bridge girders mainly including prestressed concrete(PC) bridge girders and steel bridge girders. The typical fire accidents occurred on bridges are illustrated and,...This paper presents an overview on fire behavior of bridge girders mainly including prestressed concrete(PC) bridge girders and steel bridge girders. The typical fire accidents occurred on bridges are illustrated and, the seriousness of posing threats to bridge structures resulted from increasing traffic fires, specially intense hydrocarbon fires generated from petrol-chemicals, is highlighted. The current researches, embracing high-temperature properties of constituent materials, prestress state, measurement in fire tests, numerical methods, structural fire resistance, and so forth, taken on coping with problems existing in fire behavior and structural fire behavior in bridge girders are reviewed and discussed. Further, strategies for enhancing fire resistance of bridge girders followed with failure criterion and mode in types of bridge structures are provided. Future research area along with emerging trends in structural fire behavior of bridge girders is also recommended for mitigating fire hazards occurred on bridge girders. Herein, it can be attained a conclusion from review and discussion that prestressed concrete bridge girders with thin webs, specially T-shaped bridge girder, are prone to unstable under fire exposure conditions. High-strength concrete utilized in prestressed concrete bridge girders is vulnerable to spalling at elevated temperature. Steel-truss bridge girder present a more significant fragility to fire exposure compared than other steel bridge girders.展开更多
The phenomenon called “flashover” or “eruptive fire” in forest fires is characterized by a sudden change in fire behavior: everything seems to burst into flames instantly and firefighters are overwhelmed by a sort...The phenomenon called “flashover” or “eruptive fire” in forest fires is characterized by a sudden change in fire behavior: everything seems to burst into flames instantly and firefighters are overwhelmed by a sort of eruption, spreading at a speed at far several meters per second. Unfortunately it has cost several lives in the past. The reasons for such an accident always create controversy in the research field. Different theories are highlighted and especially two major axes are currently subject to discussion because they are very popular among people involved in fire-fighting. The one with regard to VOCs emissions is the best-known among firemen. Under great heat, during summer or with a fire approaching, plants emit VOCs and the more the temperature grows, the more the amount of VOCs emitted grows. Under specific conditions (essentially topographical, meteorological and atmospheric), the cloud of gas can accumulate in an appropriate zone. The concentration of VOCs may therefore reach the Lower Explosive Limit, triggering the burst of the cloud when in contact with the fire. The second theory depends on physical considerations. An example is based on a convective flow created by the fire itself. When a fire spreads on a slope, it creates an aspiration phenomenon in a way to supply the fire with oxygen. The more this phenomenon is important, the more the flames tilt and increase the rate of speed, needing even more oxygen and thus induced flow. This vicious circle can stabilize or have an erratic behavior to trigger off a fire eruption. This article presents these two theories, and especially the new advances on this research subject.展开更多
Forest ecosystems are our priceless natural resource and are a key component of the global carbon budget. Forest fires can be a hazard to the viability and sustainable management of forests with consequences for natur...Forest ecosystems are our priceless natural resource and are a key component of the global carbon budget. Forest fires can be a hazard to the viability and sustainable management of forests with consequences for natural and cultural environments, economies, and the life quality of local and regional populations. Thus, the selection of strategies to manage forest fires, while considering both functional and economic efficiency, is of primary importance. The use of decision support systems(DSSs) by managers of forest fires has rapidly increased. This has strengthened capacity to prevent and suppress forest fires while protecting human lives and property. DSSs are a tool that can benefit incident management and decision making and policy, especially for emergencies such as natural disasters. In this study we reviewed state-of-the-art DSSs that use: database management systems and mathematical/economic algorithms for spatial optimization of firefighting forces; forest fire simulators and satellite technology for immediate detection and prediction of evolution of forest fires; GIS platforms that incorporate several tools to manipulate, process and analyze geographic data and develop strategic and operational plans.展开更多
文摘The results from a number of investigations and fire experiments are presented and analyzed in order to characterize the fire behavior of mining vehicles in underground hard rock mines. The analysis also includes fire safety and fire protection measures with respect to the mining vehicle fire behavior.Earlier studies on fires in underground hard rock mines have shown that vehicles or mobile equipment are the dominant sources of fire. A better knowledge about the fire behavior of vehicles in underground hard rock mines is therefore needed. During the analysis the direction and flow rate of the ventilation in a drift was found to have a significant impact on the fire behavior, causing for example flame tilt with rapid fire spread. The shielded sections of a vehicle will be less affected by the ventilation flow resulting in for example a decreased flame spread. It was also found that spray fires may result in considerable heat release rate but are generally of shorter duration and will not make any significant contributions to the overall heat release rate of the fully developed vehicle fire. The fire duration of a loader tire from a full-scale fire experiment was found to be at least 200 min and will largely determine the total fire duration of the vehicle. A different scenario with different conditions with for example a slower flame spread resulted in an even longer fire duration. The radiative and convective fraction will be a key factor when determining the heat transfer mechanisms involved in a fire and will vary from material to material.Calculations show that the radiative fraction of the tire fires on two mining vehicles is significantly lower than found in earlier experiments. The design and construction of the mining vehicle will have an important impact on the fire behavior and could possibly mitigate the consequences of a fire and allow fire personnel to extinguish a fire that otherwise would have had a too high heat release rate.
基金supported by the State Key Program of Coal Joint Funds of National Natural Science Foundation of China (No.51134020)the Natural Science Foundation of Shandong Province(No. ZR2011EL036)the High School Science & Technology Fund Planning Project of Shandong Province (No. JIILD53)
文摘In this study, a series of flame-retardant polyisocyanurate-polyurethane (PIR-PUR) foams were prepared using various concentrations (0-25% by weight) of expandable graphite (EG) and dimethyl methyl phosphonate (DMMP) (0-7% by weight). The effect of these additives on the properties of the PIR-PUR foams, including physico-mechanical, morphological, flame retardancy, and thermal stability, was studied. Increasing amounts of EG in the PIR-PUR foam caused a significant drop in the compression strength. However, DMMP caused the mechanical properties of PIR-PUR foam to improve compared to foam filled with EG alone. The flame retardancy of PIR-PUR foams containing both EG and DMMP was enhanced significantly compared to EG filled foams. Thermogravimetric analysis (TGA) indicated that EG enhances the thermal stability of PIR-PUR foams but that DMMP decreased it. The morphology of the residual char provided conclusive evidence for the weak thermal stability of foams filled with DMMP.
文摘To investigate the temperature field and residual bearing capacity of the sandwich wall panels with GFRP skins and a wood-web core under a fire,three sandwich walls were tested.One of them was used for static load test and the other two for the one-side fire tests.Besides,temperature probe points were set on the sandwich walls to obtain the temperature distribution.Meanwhile,the model of the sandwich wall was established in the finite element software by the method of core material stiffness equivalent.The temperature distribution and performance reduction of materials were also considered.The residual bearing capacity of specimens after fire exposure were simulated considering the effects of web spacing,wall panel thickness and fire exposure time.Because the sandwich wall panels were stressed by eccentric compression after a fire,the residual compressive strength of the wall panel after the fire can be calculated through the eccentric loading analysis.Compared with the numerical results,it can be concluded that the effectiveness of calculation method of residual bearing capacity after fire exposure was proved.
基金support from National Natural Science Foundation of China(Grant No.51878057,52078043)Shaanxi Science Foundation for Distinguished Young Scholars(Grant No.2022JC-23)+2 种基金Fundamental Research Funds for the Central Universities-CHD(Grant No.300102212907,300102210217)Michigan State UniversitySoutheast University。
文摘This paper presents an overview on fire behavior of bridge girders mainly including prestressed concrete(PC) bridge girders and steel bridge girders. The typical fire accidents occurred on bridges are illustrated and, the seriousness of posing threats to bridge structures resulted from increasing traffic fires, specially intense hydrocarbon fires generated from petrol-chemicals, is highlighted. The current researches, embracing high-temperature properties of constituent materials, prestress state, measurement in fire tests, numerical methods, structural fire resistance, and so forth, taken on coping with problems existing in fire behavior and structural fire behavior in bridge girders are reviewed and discussed. Further, strategies for enhancing fire resistance of bridge girders followed with failure criterion and mode in types of bridge structures are provided. Future research area along with emerging trends in structural fire behavior of bridge girders is also recommended for mitigating fire hazards occurred on bridge girders. Herein, it can be attained a conclusion from review and discussion that prestressed concrete bridge girders with thin webs, specially T-shaped bridge girder, are prone to unstable under fire exposure conditions. High-strength concrete utilized in prestressed concrete bridge girders is vulnerable to spalling at elevated temperature. Steel-truss bridge girder present a more significant fragility to fire exposure compared than other steel bridge girders.
文摘The phenomenon called “flashover” or “eruptive fire” in forest fires is characterized by a sudden change in fire behavior: everything seems to burst into flames instantly and firefighters are overwhelmed by a sort of eruption, spreading at a speed at far several meters per second. Unfortunately it has cost several lives in the past. The reasons for such an accident always create controversy in the research field. Different theories are highlighted and especially two major axes are currently subject to discussion because they are very popular among people involved in fire-fighting. The one with regard to VOCs emissions is the best-known among firemen. Under great heat, during summer or with a fire approaching, plants emit VOCs and the more the temperature grows, the more the amount of VOCs emitted grows. Under specific conditions (essentially topographical, meteorological and atmospheric), the cloud of gas can accumulate in an appropriate zone. The concentration of VOCs may therefore reach the Lower Explosive Limit, triggering the burst of the cloud when in contact with the fire. The second theory depends on physical considerations. An example is based on a convective flow created by the fire itself. When a fire spreads on a slope, it creates an aspiration phenomenon in a way to supply the fire with oxygen. The more this phenomenon is important, the more the flames tilt and increase the rate of speed, needing even more oxygen and thus induced flow. This vicious circle can stabilize or have an erratic behavior to trigger off a fire eruption. This article presents these two theories, and especially the new advances on this research subject.
基金co-financed by the European Union(European Social Fund-ESF)and Greek national funds through the Operational Program‘‘Education and Lifelong Learning’’of the National Strategic Reference Framework(NSRF)-Research Funding Program:Thales.Investing in knowledge society through the European Social Fund
文摘Forest ecosystems are our priceless natural resource and are a key component of the global carbon budget. Forest fires can be a hazard to the viability and sustainable management of forests with consequences for natural and cultural environments, economies, and the life quality of local and regional populations. Thus, the selection of strategies to manage forest fires, while considering both functional and economic efficiency, is of primary importance. The use of decision support systems(DSSs) by managers of forest fires has rapidly increased. This has strengthened capacity to prevent and suppress forest fires while protecting human lives and property. DSSs are a tool that can benefit incident management and decision making and policy, especially for emergencies such as natural disasters. In this study we reviewed state-of-the-art DSSs that use: database management systems and mathematical/economic algorithms for spatial optimization of firefighting forces; forest fire simulators and satellite technology for immediate detection and prediction of evolution of forest fires; GIS platforms that incorporate several tools to manipulate, process and analyze geographic data and develop strategic and operational plans.
