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15 November 2025, Volume 44 Issue 11 Previous Issue   

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Experimental study on electric bus fire ignited by overcharging of lithium batteries Peng Lei, Wu Xiaoguang, Su Ye, Yang Yuexiang, Kong Xin, Xie Ruiyun, Ni Zhaopeng, Zhang Xing, Wang Yu, Ji Jingwei 2025, 44 (11):  1585-1594.  Abstract ( 183 )   With the continuous increase in the proportion of electric buses in public transportation, the demand for charging and overnight parking of electric buses in indoor parking lots or garages is growing. However, there is little research on the fire hazards of electric buses and their influence to the surrounding buses and the garages. In this paper, a test platform was established, and a full-size burning test of an electric bus with lithium iron phosphate batteries was carried out by inducing fire through overcharging the battery packs. The test results indicate that approximately 3 minutes after the thermal runaway of the lithium batteries and the appearance of an open flame, the flame emerging from the battery compartment caused the upper window glass to break, and the flame immediately entered the cabin of the bus and quickly ignited the interior materials and seats. In the subsequent approximately 10 minutes, the fire spread rapidly from the rear of the bus to the front, resulting in a fierce combustion of the entire vehicle. The temperature and radiant heat flux intensity at a distance of 1 meter around the burning bus could reach approximately 500~685 °C and 55~84 kW/m2, respectively. The high temperature and radiant heat flux intensity might lead to the ignition of the surrounding buses. During the test, the maximum measured temperatures below the garage ceiling were mostly below 1 000 °C, but instantaneous high temperatures at a few locations could reach approximately 1 225 °C. The research results provide beneficial technical parameters for understanding the fire development patterns of electric buses and determining the fire prevention measures for electric bus stations. Related Articles | Metrics

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Study on gas generation and hazard characteristics during EV lithium-ion battery thermal runaway based on component analysis Hu Hao, Mao Ling, Peng Xinyu 2025, 44 (11):  1595-1603.  Abstract ( 100 )   Prior studies on lithium-ion battery thermal runaway often examine the gas generation characteristics under specific chemistries or single conditions, systematic sorting and in-depth exploration of the complex structure-activity relationship between the inherent characteristics of batteries (such as chemical composition, state of charge SOC) and gas hazards (flammability, toxicity) remains limited. Notably, inconsistent test conditions and methods hinder data standardization. This study integrates systematic analysis and multi-dimensional data to establish a framework for analyzing gas evolution during thermal runaway. Results show that for lithium iron phosphate (LFP) and nickel-manganese-cobalt oxide (NMC) batteries, there are significant differences in the difficulty of triggering thermal runaway and the characteristics of heat release, and the gas hazards are more complex. LFP generates less total gas, yet its mixtures have lower flammability limits and, under certain conditions, higher HF emissions than NMC. These findings underscore the need for safety evaluation from multiple dimensions such as thermodynamics, flammability, and toxicity. Related Articles | Metrics

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Study on the inhibition characteristics of CH4/coal dust composite explosion by inert gas in confined space Li Zhifeng, Ji Wentao 2025, 44 (11):  1604-1610.  Abstract ( 50 )   Gas/coal dust mixed explosion is a complex phenomenon of homogeneous-heterogeneous coupled combustion, and its dominant combustion mechanism dynamically evolves. Compared with single component explosion, it has higher explosion intensity and constitutes an important challenge in coal mine disaster prevention and control. Based on a 20 L spherical explosion testing device, this article investigates the inhibitory effects of two inert gases (N2 and CO2) on CH4/coal dust composite explosions. By comparing the changes in explosion characteristic parameters under different gas concentration conditions, the differences in explosion suppression efficiency between the two inert gases and their mechanisms of action are revealed. The research results indicate that N2 and CO2 have inhibitory effects on CH4/coal dust composite explosions under different composite conditions, with CO2 showing a significantly better explosion inhibition effect than N2. In the explosion inhibition process, both CO2 and N2 have exerted dilution and cooling effect. CO2 consumes the key active free radical H· generated during the explosion process through elementary reactions, thereby reducing the content of active free radicals in the explosion reaction system and effectively delaying the explosion reaction rate. The research results can provide theoretical basis and quantitative reference for the prevention and control of coal mine explosion disasters. Related Articles | Metrics

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Effect of ambient temperature on thermal runaway characteristics of lithium-ion batteries under overcharging conditions Li Decheng, Gong Yao, Peng Wei, Zhang Shaojie 2025, 44 (11):  1611-1618.  Abstract ( 56 )   In order to investigate the influence of ambient temperature on the safety performance of square ternary lithium-ion batteries during overcharging, the lithium-ion batteries were overcharged to thermal runaway at a charging multiplication rate of 1.5C, and some representative characteristic values were selected by analyzing the time of thermal runaway of the batteries at different ambient temperatures（30, 40, 50 ℃）, the voltage, surface temperatures at different locations, and the air pressure and gas composition generated by thermal runaway. We investigated the trend and the magnitude of change of these characteristic values （i.e., the sensitivity to the change of ambient temperature） with the change of ambient temperature. The results show that under overcharging conditions, the increase in ambient temperature accelerates the thermal runaway process and exacerbates the risk of thermal runaway. The gas production and exhaust of the side reactions significantly affect the temperature and voltage behaviors of the battery. The higher the ambient temperature, the shorter the time required for thermal runaway. The surface temperatures at most locations of the battery increase with the increase of the ambient temperature. However, the maximum temperature at the center of the battery's surface at the largest side decreases with the increate of ambrent temperature. As the ambient temperature increases, the volume fraction of CO and CO2 increase, while the concentration of CH4 decreases. The sensitivity of different characteristic values to ambient temperature varies. Therefore, according to the characteristics of different characteristic values with the change of ambient temperature, it is necessary to formulate the corresponding safety alarm thresholds in order to better cope with the change of ambient temperature. Related Articles | Metrics

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Research progress on fire prevention and safety performance of new energy batteries Liu Yuzheng, Li Xiangzhuochun, Cao Ruihan 2025, 44 (11):  1619-1631.  Abstract ( 70 )   This paper systematically reviews the research progress on the thermal runaway mechanisms, material-related factors, fire suppression technologies, and safety protection strategies of hydrogen fuel cells and lithium-ion batteries. A comparative analysis is conducted on the applicability and limitations of extinguishing agents such as liquid nitrogen, HFC-227ea, and Novec-1230 under different operating conditions. The study reveals that the current safety design for hybrid hydrogen-lithium systems remains at an early stage. In response to the emerging fire safety demands of hybrid energy storage systems, this paper proposes five forward-looking research directions, including multimodal sensing and response systems, coordinated thermal management frameworks, hybrid extinguishing agents, and modularized safety compartment design. The development prospects of these approaches are evaluated from the perspectives of materials science, systems engineering, and fire safety technology. The findings aim to provide theoretical and technical support for the fire protection design and standardization of high-integration, multi-energy storage systems in the future. Related Articles | Metrics

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Study on the mechanical properties of flame-retardant polyurethane for fire containment Feng Yubo, Li Zhong, Zhao Xuedong, Lyv Dong 2025, 44 (11):  1632-1636.  Abstract ( 37 )   This paper analyzes the force acting on containment dikes used in firefighting spill control and establishes a calculation model for dike setup parameters. It proposes that the height of fluid that a polyurethane dike can block during use is directly proportional to its thickness. When flame-retardant polyurethane is combined with cement, the horizontal tensile force it can withstand is proportional to the square of its thickness. Using modified flame-retardant polyurethane as the containment material, the parameters of the calculation model are determined through experiments, and the error of the model is assessed. Related Articles | Metrics

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Simulation on the degradation characteristics of cable insulation materials under temporary high temperature of fire Cai Jing, Guo Wei, Li Huachun, Ji Hongquan, Ren Zhigang 2025, 44 (11):  1637-1643.  Abstract ( 69 )   When a tunnel fire occurs, the high-voltage cables near the fire source are temporarily exposed to high temperatures. The degradation characteristics of cross-linked polyethylene (XLPE) cable insulation material after high temperature of fire need to be studied. Firstly, a simulation model is established to analyze the temperature variation curve of the cable insulation layer under typical fire conditions in this paper. Then the heat treatment platform is built. XLPE samples are processed according to the equivalent temperature rise curves with the highest temperatures of 300, 325, 350 ℃. Finally, the microstructure, functional groups, crystallinity, and breakdown field strength of the sample are tested. The results indicate that as the degradation temperature increases, the regularity of the sample surface gradually decreases. The polymer fragments and small molecular substances generated by XLPE molecule breakage aggregate together to form a granular structure. The crystallinity decreased from 28.67% to 16.47%. The carbonyl index increased from 0.022 to 0.344, and the hydroxyl index increased from 0.066 to 0.211. The breakdown field strength decreased from 74.16 kV/mm to 50.38 kV/mm. The research results can provide theoretical basis for the degradation assessment and maintenance replacement of cable insulation after fire accidents. Related Articles | Metrics

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An improved CBUF-based predictive model for the heat release rate of mattress combustion Lu Weitian, Liu Jianyong, Duan Jintao, Gao Shijie, Wu Xin 2025, 44 (11):  1644-1649.  Abstract ( 31 )   To address the discrepancy observed in the CBUF model when predicting the heat release rate (HRR) of large-scale mattresses, a method is proposed in which data from multiple thinner specimens tested using a cone calorimeter are superimposed. This approach approximates the more rapid vertical heat penetration observed in full-scale specimens. Cone calorimeter and furniture calorimeter tests were conducted based on the model’s input parameters. In the full-scale experiments, flame area was quantified using machine vision techniques, and a sensitivity analysis of the model was performed. The model results demonstrate that the predicted HRR values generated by this method show good agreement with the measured values, particularly improving accuracy during the decay phase of the HRR curve. This indicates that for thicker polyurethane (PU) foam materials, the vertical heat penetration rate in full-scale experiments is faster than that implied by the corresponding cone calorimeter data. Consequently, the HRRPUA curve obtained from full-scale experiments tends to resemble a “single-peak” profile rather than the “double-plateau” shape typically seen in cone calorimeter tests. Related Articles | Metrics

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Experimental study on combustion characteristics of high-density polyethylene hollow blow molded folding seats Zhao Yu, Yu Zeyang, Peng Lei 2025, 44 (11):  1650-1656.  Abstract ( 51 )   Through conducting combustion characteristic experiments on high-density polyethylene (HDPE) hollow blow molded folding seats, the combustion characteristics and propagation patterns of seats arranged in different configurations were investigated. Metrics such as heat release rates and seat temperatures were measured, and pertinent parameters, including the fire growth coefficient, were analyzed. The test results indicate that once ignited, HDPE hollow blow molded folding seats with B1 combustion classification reach a maximum combustion temperature of approximately 850 ℃, with a peak heat release rate ranging of 70~132 kW. The fire growth coefficient (α) is approximately 0.001 kW/s2, slightly slower than that of a slow-burning fire. The fire basically does not propagate to seats on either side or to those in the front row or behind row. Observations from the combustion processes of the experiments reveal that HDPE hollow blow molded folding seats melt during combustion, resulting in flowing fire of the dripping plastics. Consequently, for sports venues equipped with HDPE hollow blow molded folding seats, consideration should be given to measures to prevent the spread of fire caused by flowing fire. Related Articles | Metrics

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A review of research on natural smoke exhaust by vertical shafts in tunnel fires Gao Zihe, Zhao Pengju, Cai Jiajun, Weng Miaocheng 2025, 44 (11):  1657-1664.  Abstract ( 43 )   This article comprehensively evaluates the research results on natural smoke exhaust by shafts in tunnel fire, aiming to promote the development of tunnel fire prevention and disaster relief research, and provide theoretical basis and technical support for tunnel fire prevention design. The article systematically reviews the current research status of natural smoke exhaust by shafts in tunnel fire, briefly describes the main research methods and basic principles of natural smoke exhaust by shafts in tunnel fire, and summarizes in detail the research progress in this field at home and abroad. The research focuses on the impact of various factors such as the vertical shaft (height, size and shape of the vertical shaft, distance between the vertical shaft and the fire source, number and arrangement of vertical shaft), environment (environmental pressure, environmental wind), and tunnel structure (degree of tunnel blockage, tunnel slope, tunnel height to width ratio) on the natural smoke exhaust from vertical shafts in tunnel fires. In addition, some methods for improving the smoke exhaust performance of vertical shafts (inclined vertical shaft structure, vertical shaft-smoke curtain and vertical baffle structure, vertical shaft plate coupling structure) were also introduced, so as to provide reference for tunnel fire prevention and disaster relief research. Related Articles | Metrics

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Discussion on the use of sunken plaza for fire evacuation design Qi Xiaoxia, Qin Shengmin, Zhang Jiawei, Tian Yumin 2025, 44 (11):  1665-1669.  Abstract ( 62 )   When the sunken plaza is only used for evacuation, if the provisions of Article 6.4.12 of the GB 50016-2014， Code for Fire Protection Design of Buildings are implemented, it is often difficult to design because of the horizontal distance requirement of 13 m between the openings and the minimum area requirement of 169 m2 for the sunken plaza. However, there are no other fire protection design requirements for sunken plazas used for evacuation in the current national standards. In response to the chaotic design of sunken plazas and considering the actual engineering design requirements, this paper proposes a fire protection design method for sunken plazas used for evacuation within the current framework of Code for Fire Protection Design of Buildings. It emphasizes that all design requirements for sunken plazas used for evacuation should be based on the size of open-air openings. By using calculations, it links the area of open-air openings in sunken plazas, the width of outdoor staircases, and the calculated clear evacuation widths of each fire compartment leading to these sunken plazas, achieving the goal of quantitatively reducing the evacuation width. Additionally, a brief discussion is provided on the fire protection design of superimposed sunken plazas and sunken plazas shared by subway and commercial areas. Related Articles | Metrics

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Design and implementation of fire protection standards question answering system using large language model Guo Ge, Hu Rui, Ren Changxing, Huang Jinzhu, Wei Jidong 2025, 44 (11):  1670-1676.  Abstract ( 54 )   As an authoritative standard for design, construction, and supervision, fire protection standards play a crucial role in ensuring work safety. However, the interpretation and implementation of standards have relied on the experienced operations of professionals and manual verification. To address this issue, this paper designs a question-answering system for fire protection standards based on large language models and retrieval augmented generation, realizing the knowledge question-answering function in the professional field of fire protection standards and specifications. The system consists of a large language model, an external knowledge base, and a user interface. To improve the retrieval quality of the knowledge base, a retrieval algorithm weighted by professional terms is proposed. A set of question optimization templates suitable for fire protection standards is constructed to enhance the accuracy of users' question and the quality of the system's answers. Considering data security, a lightweight local deployment is achieved. The practical tests show that the question-answering system can accurately answer questions related to fire protection standards and has good stability and practicality. The development of system has opened up new ideas for the intelligent expression recognition and content analysis of fire protection standards, and it represents a beneficial exploration of large language model technology in the field of smart fire protection. Related Articles | Metrics

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Research progress on intelligent thermal protective suits based on CiteSpace Lu Xinyi, Gao Peng, Lu Yehu 2025, 44 (11):  1677-1683.  Abstract ( 43 )   To conclude the research and future trends of intelligent firefighting suits, this paper uses information visualization and network analysis methods to creat a visual information graph based on literature from the Web of Science (WoS) and China National Knowledge Infrastructure (CNKI) databases from January 1999 to June 2024 serves as the data source. The results show that South Korea, India, China and USA are the main research countries, with Donghua University, the Hong Kong Polytechnic University, China Academy of Sciences and Soochow University accounting for the majority of the core institutions. Research hotspots are human thermal physiology and comfort, workers' safety protection, and textile sensor technology. The paper also focuses on the composition of intelligent firefighting suits, intelligent safety assessment systems, and the innovative application of integrating various sensors with flexible electronic textiles. The development of a personnel safety assessment system based on intelligent firefighting suits is a future research direction in the field of firefighting, providing references and suggestions for the development of intelligent firefighting suits that combines comfort and safety. Related Articles | Metrics

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Practice and prospect of Fujian province's intelligent fire service platform construction Chen Bingan 2025, 44 (11):  1684-1689.  Abstract ( 63 )   In order to solve a series of problems in traditional fire supervision, such as the lack of implementation of unit main responsibility, insufficient self-management initiative, weak joint management and collaboration among departments, numerous data barriers that are difficult to integrate, and the inability of regulatory methods and quality to adapt to new challenges, it is necessary to promote the transformation of traditional fire protection into intelligent one. Taking the intelligent fire service platform of Fujian Province as a case study, this paper analyzes the platform's overall strcuture, its 7 core pillars, 13 subsystems, and key implementation strategies. It also presents specific examples of system collaboration. Finally, the paper offers a forward-looking view on the future of intelligent fire protection, providing effective solutions and a model for fire safety management both in Fujian and other provinces. Related Articles | Metrics

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Research on the effectiveness of fire science and technology resources in responding to major and extremely serious disasters Wang Wei 2025, 44 (11):  1690-1697.  Abstract ( 40 )   The deployment of fire science and technology resources in responding to major and catastrophic disasters represents a vital innovation for enhancing firefighting and rescue capabilities and advancing fire science and technology. This paper systematically reviews and analyzes practical operations in which scientific and technological teams have supported fire fighting and rescue efforts during major disaster accidents. Based on this analysis, an effectiveness evaluation method for mission deployment supported by fire science and technology resources is proposed, utilizing an AHP-fuzzy comprehensive evaluation model. The evaluation index system constructed in this method comprises 9 indicators across 3 dimensions: the effectiveness of actual rescue operations, the application of scientific and technological achievements, and the improvement of research and development efficiency. Indicator weights are determined based on expert scoring. A quantitative evaluation was then conducted to assess the effectiveness of a deployment task, with results categorized into 4 levels: excellent, good, medium and poor. This study aims to explore a new pathway for improving the deployment mechanism of fire science and technology resources and facilitating the technology transfer. Related Articles | Metrics

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Research on method for identifying the factors causing community fires based on Internet information Han Chong, Zhang Wei 2025, 44 (11):  1698-1703.  Abstract ( 36 )   In this article, we propose a method for mining disaster-causing factors in community fires based on information from the Internet. It collates dynamic data reflecting the lives of community residents from open maps, housing rental and sales information, merchant information, and relevant netizen comments, comprehensively use text mining, time series signal analysis, and other methods to study and judge the future fire situation and key data characteristics of the community. It also uses netizen comments to mine hidden community fire factors, and ultimately achieves the goal of dynamically identifying disaster-causing factors in community fires. The method can be used to assist the dynamic updating of community fire prevention strategies for fire management, departments and provide a new way of thinking for dynamic prevention and control of community fires. Related Articles | Metrics

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Research on fire prevention and control technologies for Ro-Ro new energy vehicle ships Dai Xiaoying 2025, 44 (11):  1704-1707.  Abstract ( 58 )   By conducting research and analysis on fire prevention and control technologies for Ro-Ro new energy vehicle (NEV) ships at home and abroad in recent years, this study sorts out the major technological advancements in early fire detection and early warning, fixed fire suppression technologies, and emergency response technologies/equipment for Ro-Ro NEV ship fires. It summarizes the key challenges that still need to be addressed, including the single means of detection and early warning, delayed response, low efficiency in extinguishing deep-seated fire sources with high re-ignition risk, lack of multi-level comprehensive prevention and control strategies, and inefficient application of emergency response equipment. Corresponding solutions are proposed, such as enhancing early detection and early warning technologies, promoting the development of multi-agent combined fire suppression systems and new fire-extinguishing agents, and strengthening multi-level protective and response technologies/equipment. This study aims to provide technical guidance for fire prevention and control of Ro-Ro NEV ships and contribute to the safe development of the industry. Related Articles | Metrics

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Study on identification and traceability of diesel based on chemical fingerprint and stable isotope fingerprint Tian Guihua, Fan Zilin, Deng Zhenyu, Wang Mian, 2025, 44 (11):  1708-1713.  Abstract ( 32 )   Source identification study on diesel fuels with varying degrees of weathering was conducted using gas chromatography-mass spectrometry (GC-MS) and isotope ratio mass spectrometry (IRMS) techniques. By analyzing the GC-MS chemical fingerprint characteristics of n-alkanes in 43 diesel samples across 8 weathering levels, the boundary conditions for diesel source identification based on chemical fingerprints were determined. Analysis of total carbon and monohydrocarbon isotope ratios in the diesel samples yielded isotopic fingerprints. Linking these isotopic fingerprints with the chemical fingerprints enables more effective differentiation between diesel fuel sources, providing support for fire investigation. Related Articles | Metrics

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Investigation and reflections on a continuous explosion accident of a large tanker Rao Qiufei 2025, 44 (11):  1714-1718.  Abstract ( 41 )   The investigation and handling of a major oil tanker explosion and burning accident is introduced, which involves the short-term continuous explosion and burning of oil tanks, and all the operators on the site died on the spot, and it is difficult to decide the initial explosion point and ignition source. Through on-site investigation, inspection appraisal, video analysis, expert demonstration and other means, the initial oil tank and ignition source of the explosion accident were successfully identified by using comprehensive methods such as analysis, reasoning and detection. At the same time, the technical characteristics of the ship fire and explosion accident investigation are summarized, and work suggestions on the fire investigator as an expert to attend the trial are put forward. Related Articles | Metrics

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Investigation and research on fire induced by arcing faults in photovoltaic connection terminals Zhang Liang, Liu Zonghong, Huang Meng, Jiao Lei, Chen Ke 2025, 44 (11):  1719-1724.  Abstract ( 54 )   Fires caused by photovoltaic (PV) systems occur from time to time. The special structure of PV systems, difficulties in background data analysis and diverse fault modes bring significant challenges to fire investigation. Starting from a fire case involving a rooftop PV system of a factory building, this paper identifies the fire origin and cause through on-site trace analysis and physical evidence collection, and further verifies the accident cause via a 1：1 scale simulation test. The study reveals that fires triggered by arcing due to poor contact at single-phase connection terminals of PV systems exhibit the following characteristics: arc marks are formed at the contact points of single-phase terminals, and abnormalities occur in the background operation data, such as fault alarm information related to voltage, current, and leakage current. Related Articles | Metrics

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Thermal damage traces characteristics and formation mechanism of buried bodies in fire scenes based on case analysis Li Xuejun, Lyu Li, Jin Jing 2025, 44 (11):  1725-1730.  Abstract ( 41 )   Compared with exposed corpses in fire scenes, corpses buried under collapsed objects show characteristics of thermal damages due to factors such as occlusion by buried objects and complex fire scene environment, and further research on the characteristics and formation mechanism of thermal damages on such corpses has important value for the theory and practice of fire scene investigation. However, there is a lack of systematic research on the thermal damage characteristics of buried corpses, and the formation mechanism of corpses under the coupling action of multiple factors such as buried medium, fire scene temperature gradient, and burning time is still unclear, resulting in the difficulty of precisely analyzing the thermal damage of such corpses in actual cases. To this end, this article selects typical fire scene burial corpse cases, systematically describes the characteristics of thermal damage traces on human skin, fat, muscle, bone and other parts under the condition of burial, the formation mechanism and its role in reconstructing the scene, and provides scientific basis and theoretical support for the determination of the of death, the identification of the cause of damage and the reconstruction of the fire scene in case solving. Related Articles | Metrics