The use of Petri nets and a two-zone model for fire scene reconstruction

Fire scene investigation relies on in situ investigation (observations that take place where the fire occurred) and laboratory analysis. Nowadays the role and place of fire modelling in fire forensic investigation are debated within the forensic community. The main objective of this work is to propose a methodology to consider the stochastic aspect of fire development in a specific case by using fire modelling. Therefore, a stochastic fire safety engineering tool so-called SCHEMA-SI (Stochastic Computation and Hybrid Event Modelling Approach-Sécurité Incendie) developed at the CSTB (French Scientific and Technical Construction Centre) has been used to reconstruct a fire scene that occurred in 2007 in a senior care facility situated in the Paris suburb (France). In this case study, several fire scenarios were generated with SCHEMA-SI from probabilistic data in order to perform fire scene investigation. Each scenario is composed on one hand by a succession of dated events and on the other hand by physical quantities time-evolution at different locations in the building (heat release rate, temperature, interface height…). The objective of this work was to find the scenarios which allow getting an acceptable agreement between the calculated values and the observations from the real situation in the fire scene. Among the thousands of fire scenarios generated, 20% were compliant with the fire scene observations. The analysis of these compliant scenarios gave a better idea of what might have happened in the care facility. At the end, the contribution of numerical simulation in a fire scene analysis is discussed.     

油氢合建站典型泄漏火灾热辐射后果模拟分析

根据油氢合建站实际运行状态识别典型火灾事故场景,建立高压氢气泄漏喷射火及油池火灾事故热辐射模型,模拟分析油氢合建站地面涉氢设施及加油设备典型泄漏火灾危害特性.结果表明:储氢区涉氢压力45 MPa、发生典型10 mm泄漏喷射火时危害范围较大,对设备及人员危害距离分别为21 m和36 m;加油枪断裂发生40～60 L/mi...     

商业厨房火灾烟气蔓延数值模拟研究

通过实地调研得到典型商业厨房物理模型。设置8种工况,利用CFD模拟商业厨房不同火灾事故场景下的烟气、温度、能见度等参数的变化规律,得到不同火灾事故场景的演化特点。分析结果可知,商业厨房发生火灾约30~40 s后,厨房内2 m高度处截面的能见度降到10 m以下,影响人员疏散;发生火灾约50~150 s后,门口1.8 m高度处测点温度达到60 ℃,影响人员的生命安全。     

氢燃料电池应用燃爆风险与防治研究现状

氢燃料电池汽车 HFCV 是我国新能源汽车发展的重要方向,HFCV 和加氢基础设施消防安全理论和规范标准亟需完善。分析 HFCV 和加氢站的火灾燃爆危险性与消防安全形势,综述了在高压氢泄漏可能导致的射流冲击、扩散积聚、射流燃烧和气云燃爆等多种灾害场景方面的研究进展,并探讨了现阶段高压氢能消防研究方面存在的问题和局限性,展望了氢能消防安全研究方向。     

Analyzing fire-induced dispersion and detector response in complex enclosures using salt-water modeling

The current investigation examines suitability of the hydraulic analog for analysis of fire-induced dispersion within a complex enclosure. This analog has been implemented using salt-water modeling and planar laser induced fluorescence (PLIF) diagnostics providing quantitative visualization of simulated fire-induced flows. The non-intrusive PLIF diagnostics are used to temporally and spatially characterize dispersion from a buoyant source within a 1/7th scale room–corridor–room enclosure. This configuration is geometrically similar to a full-scale fire test facility, where local fire conditions were characterized near five ionization type smoke detectors placed throughout the enclosure. The full-scale fire and salt-water model results were scaled according to the dimensionless fundamental equations that govern source dispersion.An evaluation of the local conditions and dispersive event times for both the systems was used to explore the ability of the hydraulic analog to predict smoke detector response times. The dispersive event (front arrival) times predicted by the salt-water model, which represents a necessary event for detector activation, were in excellent agreement with the fire test data. A methodology using these front arrival times along with local conditions at the detector location is introduced in this paper. However, the complex nature of detector response and fidelity limitations of the analog make precise predictions of detector response time challenging. The predicted dimensionless response times were within 25% for all detector locations, with the exception of the first-room ceiling detector location. For this latter, a shorter dimensionless response time by less than 40% of that in the actual fire was predicted.     

临时加氢站火灾爆炸风险评估及防范对策

对临时加氢站的火灾爆炸危险性进行分析,辨识场站的重大危险源,对移动加氢车和氢气长管拖车上的高压氢气集装管束进行火灾爆炸事故后果模拟分析。计算得到临时加氢站发生蒸气云爆炸和喷射火事故的死亡半径、重伤半径和轻伤半径,提出临时加氢站的重点防范区域,以弥补因临时加氢站选址和防火间距不足带来的火灾隐患和先天缺陷,为减少或降低临时加氢站发生火灾爆炸对人员和财产的危害提供技术依据。     

Analysis and optimization of ventilation systems for an underground transport interchange building under regular and emergency scenarios

The work and conclusions gained from the analysis of five new underground interchange buildings ongoing in Madrid, Spain, is presented. An additional study was performed for a typical two-level interchange building, and the methodology and results are presented in this paper.First, different ventilation and air conditioning strategies have been analyzed. The main goal is to find the most efficient design in order to maintain pollutants concentration and temperatures below the designed values, at minimum investment and operation costs. Different strategies have been modelled and compared using a Computational Fluid Dynamics (CFD) code, taking into account the buses circulation and the different pollution and heat sources. The final solution developed is based on a physical separation between the island area and the dock area. Conclusions on the efficiency of the different design strategies and possible pitfalls are presented.Secondly, different fire scenarios are analyzed. The main goal is to check whether the fire fighting measures planned, such as mechanical ventilation and a curtains system to define smoke sectors are able to cope with a fire emergency situation. A model for the bus fire has been developed, including heat release and smoke production. The main results presented are temperature fields, visibility and smoke concentration.     

Failure behavior of unbonded bi-directional prestressed concrete panels under RABT fire loading

Although the number of terror-and explosion-related incidents associated with military and terrorist activities is increasing globally, the existing design procedure for civil infrastructures does not consider a protective design for extreme loading scenarios such as blast, impact, and fire loading. Major infrastructure, for example bridges, tunnels, prestressed concrete containment vessels (PCCVs), and liquefied natural gas (LNG) storage tanks are often constructed using prestressed concrete, because it enhances the structural capacity. Concrete is often used as a construction material because of its low thermal conductivity, which makes it a good fire resistant material. However, the fire-resistant behavior of the high-strength concrete (HSC) and prestressing (PS) tendons used in prestressed concrete (PSC) is different than that of ordinary reinforced concrete (RC). Also, there has been limited research comparing PSC to RC under extreme loading conditions. This study presents experimental testing of unbonded bi-directionally prestressed concrete panels with dimensions 1000×1400×300 mm³ that were tested under RABT fire loading to simulate a jet aircraft crash-fire accident. A prestressing force of 430 kN was applied to the PSC specimens using unbonded threaded bars. After a RABT fire test, residual flexural strength tests were performed on the fire-damaged PSC and on RC specimens for comparison. Results of the RABT fire and residual flexural strength tests indicated that the fire-damaged PSC specimens showed severe thermal spalling damage induced by PS relaxation and deterioration of strength/stiffness, respectively. These study results can be used as basic research data for future research in numerical simulation of fire and the design of PSC structures under the fire scenario.     

电缆隧道火灾分析及计算机模拟

对电缆隧道火灾进行了分析,应用火灾动力学模拟软件FDS对电缆隧道火灾过程进行了计算机模拟,并对其火灾发展过程和防火保护措施进行了初步讨论。结果表明,电缆隧道为高火灾危险场所,在火灾情况下,隧道内维持较高温度,电缆将持续燃烧,火灾具有发展迅速、结构可能严重损伤、烟气量大、有害气体浓度高、扑救困难等特点,对其火灾危害性应引起足够重视。     

基于故障树和贝叶斯网络的建筑施工火灾风险评价

针对建筑施工现场频繁发生的火灾事故,将这一事故作为顶事件并分析导致顶事件发生的基本事件,构建故障树,表示出各基本事件与顶事件之间的逻辑关系。再将故障树转化成贝叶斯网络模型,通过贝叶斯网络的推理能力计算出顶事件发生的概率和各基本事件的后验概率。计算出各个基本事件的结构重要度、概率重要度、关键重要度,分别对三类重要度进行排序,定量地评估建筑施工火灾风险发生的可能性,找出最薄弱的环节,有针对性地指导现场施工。并引用案例数据计算施工过程中火灾事故的风险值,证明了将故障树与贝叶斯网络模型结合分析建筑施工安全风险这一方法的有效性和简便性,找出最能影响顶事件发生的风险因素,以及最容易降低概率的风险因素来更好地指导施工,将火灾风险降低到最小。     

Image-based modeling of built environment from an unmanned aerial system

In recent years, the modeling from images, called image-based modeling, is emerging as a powerful alternative for the as-built three-dimensional (3D) reconstruction of complex scenarios compared with the use of laser scanner technology or classical topographic methods. Image-based modeling is a non-invasive and low-cost technology that allows 3D reconstruction of objects and scenarios by using only images. However, although several tools currently exist for converting from two-dimensional (2D) to 3D, the specific requirements of quality and completeness for these types of scenarios are difficult to determine.In this paper, a methodology for automatically reconstructing 3D complex scenarios, particularly electrical substations, using images acquired from an unmanned aerial system is analyzed and proposed. This methodology has been incorporated by the Iberdrola Company as an optimal technique for obtaining low-cost 3D as-built metric models of electrical substations. The results obtained show that this camera-based low-cost system is a competitive alternative to laser scanning systems for modeling as-built complex constructions and can become an essential tool for facility planning and management tasks.     

Optimization of Emergency Ventilation Strategies in a Roadway Tunnel

In order to evaluate the effectiveness of in-place emergency ventilation strategies to control smoke spread in the event of a fire in a section of a roadway tunnel, both numerical and experimental studies were performed. The experimental study was conducted to provide the necessary initial and boundary conditions for the numerical phase of the investigation. A fire heat release rate of 1 MW was used in all fire tests. This fire heat release rate was selected to minimize the risk of damage to the tunnel and its associated systems while producing reliable data for visualizing the smoke movement in the tunnel. The numerical study used Computational Fluid Dynamics, Fire Dynamic Simulator version 4.0 to investigate smoke removal in the tunnel for large fire of 30 MW (bus or truck on fire). In total, four field fire tests and seven numerical simulations were conducted. Based on the study results, recommendations were made to optimize the ventilation scenarios in the tunnel section. This article presents the details of the study as well as the recommendations made.     

基于GIS的氯化氢泄漏事故后果评价

国内多晶硅的生产多采用改良西门子法,作为主要原料之一的氯化氢,其合成装置具有火灾、爆炸、中毒危险性,一旦发生泄漏将对周围环境和人员造成极大危害。以国内典型的多晶硅生产企业为例,对不同模式和场景下的氯化氢气体泄漏进行了后果模拟分析,并在GIS系统上实现了可视化输出,给出了不同情况下的危害范围和所涉及部分地区的室内外体积分数变化曲线,为应急救援和人员疏散提供决策依据。     

一起机械故障导致的公交车火灾的调查#br# #br#

介绍了一起公交车火灾事故的调查,通过现场勘验、调查询问、综合分析等手段,认定起火原因为机械故障导致天然气泄漏,遇撞击或电线短路产生的火花引起火灾。从火灾调查入手,介绍了天然气公交车火灾的调查过程,总结办案经验与体会,对天然气车辆火灾的办理起指导作用。     

Quantifying Generalized Residential Fire Risk Using Ensemble Fire Models with Survey and Physical Data

Understanding and quantifying property loss fire risk is critical to enabling decision makers in the fire field to make informed decisions. For example, the impact of various decisions made by fire departments on the fire risk in their community, while qualitatively understood by most parties, is not well quantified. Lack of quantification can lead to misdiagnosis and miscommunication on the value of services that result in sub-par resource allocations that negatively impact constituencies. Additionally, the confounding effects between fire department performance and fire risk in publicly available fire data can cause standard regression models to supply counter-intuitive conclusions based upon valid correlations (due to certain critical variables that are difficult to collect and thus unobserved). A methodology is presented that utilizes United States housing, room layout, and fire incident data, as well as experimental heat release rates, material degradation rates, and thermophysical property data in conjunction with physical fire models to estimate a community-averaged extent of fire damage in homes. Housing layout data for single family residential homes were collected from the American Housing Survey. Five home categories representing 45% of U.S. homes were selected for analysis. The U.S. Fire Administration National Fire Incident Reporting System database was used to select the distribution of initial fuels and ignition locations. Survey data was taken to specify furniture layout within the homes. A total of 5167 scenarios were developed for the combinations of home geometry, first item ignited, and furniture layout. Fire evolution was predicted for these scenarios using CFAST and coupled to a pyrolysis-inspired damage model using heat flux to targets in the homes. A damage evolution probability function was constructed for the ensemble of home and furnishing layouts and ignition distributions. This damage model was exercised in a decision analysis problem to demonstrate the utility of the methodology for community-scale resource allocation. Sensitivity studies on the model are likewise performed, indicating the largest source of uncertainty to be linked to the choice of surrogate material properties when calculating home damage. Comparison to best available data is made to assess the robustness of the model.     

Modeling carbon black trace in building fire and its validation

The carbon black trace is an important characteristic in a building fire accident and becomes crucial evidence in fire investigation. Based on the particle deposition theory, the mathematical model is established for the carbon black trace in a building fire. The numerical model of the carbon black trace is implemented into the Fire Dynamics Simulator (FDS) software. The total mass of the carbon black particle deposited on the wall surface can be calculated quantitatively and be simulated visually. The proposed model is applied into a fire accident as a validation. A numerical model is used to simulate the fire accident. In numerical simulations, the grid size resolution is analyzed. The accident reconnaissance data, accident interview record and accident scene photo/video are compared with the results of numerical simulations. It shows that the simulation results have a good agreement with those in the fire accident, which validates the mathematical model in this study. The proposed method can provide useful data for fire reconstruction and fire investigation.     

火灾中人员伤亡原因及疏散行为

根据火灾调查取得的有关参数,使用FDS火灾模拟软件对火灾过程进行了模拟,取得了楼梯间内一氧化碳、二氧化碳、氧气含量及能见度等模拟数据。燃烧产物毒害性、高温烟气、烟气减光性是火灾中致人伤亡的原因。针对火灾中人员的疏散行为,分析了火灾事故教训,提出了预防伤亡的措施。     

超细干粉灭火设备在涂装作业场所中的应用

由于油漆和溶剂具有易燃易爆的特性,涂装作业场所的火灾爆炸危险性很大,一旦发生事故,会造成巨大的财产损失和人员伤亡。针对此类场所火灾爆炸事故的特点,对超细干粉灭火设备对此类场所火灾爆炸事故的控制能力进行了讨论,并结合实例进行了超细干粉灭火设备在涂装作业场所应用的设计及计算。     

An integrated approach for tactical monitoring and data-driven spread forecasting of wildfires

In recent times there have been increasing efforts to integrate technology into wildfire management, especially in the fields of tactical monitoring and simulation. On the one hand, thermal infrared imaging (TIR) systems have been installed aboard surveillance aircraft including unmanned systems (UAS). On the other, there exists a variety of models and simulators able to forecast the fire spread. However, both fields currently present significant limitations. While relevant information is still extracted manually from aerial thermal imagery and is most times merely qualitative, simulators’ accuracy on fire spread prediction has proved insufficient. To solve these issues, this article presents a twofold methodology to couple meaningful automated wildfire monitoring with accurate fire spread forecasting. The main goals are to, firstly, automatically process aerial TIR imagery so that valuable information can be produced in real time during the event and, secondly, use this information to adjust a Rothermel-based simulator in order to improve its accuracy on-line. The fire perimeter location is tracked automatically through an unsupervised edge detector. Afterwards, an assimilation module uses the remotely sensed data to optimise the simulator's fuel and wind parameters, which are assumed to remain constant for a certain period of time. Subsequently, the optimum parameters’ values are used to issue a fire evolution forecast. All outputs are projected onto the corresponding Digital Terrain Model (DTM) and integrated into a Geographic Information System (GIS) for visualization. The global system was validated using two large-scale experiments. If these algorithms can be applied to a sufficiently rich and varied set of experimental data and further developed to cope with more complex scenarios, they could eventually be incorporated into a fire management decision support system.     

Jet fires and the domino effect

The direct effects of a jet fire are among the least severe of the diverse fire accidents that can occur in industrial installations or in the transportation of hazardous materials. However, jet fires often affect equipment (e.g., a pipe or tank) that may subsequently fail and ultimately amplify the scale of the accident. This process, known as the domino effect, can have severe consequences in accidents that involve a jet fire. However, no studies have been carried out on its significance. A survey performed on data taken from several accidents databases has revealed the most frequent accident sequences. In 50% of the reported cases involving a jet fire, an additional event with severe effects also occurred.