In order to prevent high-level fire hazards such as spontaneous combustion of top coal and upper layer residual coal，a self-produced gas expansion slurry was prepared by taking industrial solid waste phosphogypsum as the base material，adding components such as sodium bicarbonate and polyacrylamide. Firstly，a thermogravimetry(TG) analyzer was used to study the thermal stability of the slurry at different heating rates. Then，a self-built insulation performance testing system was used to test the thermal insulation performance of the slurry. Finally，the fire extinguishing and cooling performance of the slurry was studied through fire extinguishing experiments. The results show that when the temperature of phosphogypsum based self-produced gas expansion slurry is below 160 ℃，there is a mass loss of 35% to 46% in the slurry. When the temperature is above 160 ℃，the mass fraction of the slurry no longer changes. The thickness of the slurry accumulation reaches 30 mm，and the effective insulation time exceeds 139 min，which can achieve good coverage of coal spontaneous combustion hazardous areas. The slurry expands and diffuses in the cracks of the coal pile，completely enveloping the broken coal from bottom to top，isolating oxygen，and having good cooling and fire extinguishing performance. After 36 min of grouting，the temperature at all points has been decreased to below 50 ℃，and no reignition phenomenon has occurred.

In order to realize the effective rescue of various complex rail transit accidents，the present situation and development trend of the existing rail fire rescue systems at home and abroad were analyzed through a literature search first. Then，the applicability of road and rail dual-purpose vehicles in mountain urban rail transit systems and the feasibility of modular transformation were summarized and analyzed. Finally，a new fire and rescue rail transit system was proposed，which was suitable for mountain urban rail characteristics. The results show that the designed road and rail dual-purpose fire rescue vehicle meets the requirements of track fire rescue. The system is adopted with a high-intensity modular and prefabricated design concept. It is equipped with a fire extinguishing and smoke exhaust system for controlling various fire conditions，a traction winch，emergency power generation，medical supplies，and other emergency rescue equipment，which can deal with the rescue work of track accidents in a closed and heavy smoke environment. The loss caused by accidents is significantly reduced.

In order to ensure the safety of the construction and operation of the karst water inrush tunnel，based on the elastic beam model，double cusp mutation model of the instability of the karst water inrush roof under dynamic disturbance was established by using the catastrophe theory. Considering the surrounding rock properties，hydrostatic pressure，dynamic disturbance and other factors，the instability mechanism and failure conditions of the roof of karst water inrush tunnel were analyzed，the discriminant equation of its instability mutation was established，and the minimum safe thickness of the roof was solved by Matlab software programming. At the same time，in order to avoid the irrationality of the theoretical formula of the mutation when the hydrostatic pressure was too large，the minimum safe thickness of the hydrostatic pressure was calculated separately，and the greater value of two calculated values was taken. The results show that whether the waterproof rock mass remains stable is determined by the factors the internal and external factors of rock mass. The minimum safe thickness of the rock mass increases with the increase of the span of the rock mass，and decreases with the increase of the elastic modulus of the rock mass. When the vibration frequency is constant，the greater the blasting load，the greater the minimum safe thickness of rock mass. When the blasting load is constant，the greater the frequency of blasting vibration，the smaller the minimum safe thickness of rock mass. The greater the hydrostatic pressure，the greater the minimum safe thickness of rock mass. The engineering example shows that this method of calculating the safety thickness of the roof of karst tunnel is feasible and highly accurate.

To effectively prevent and control coal mine underground belt conveyor fire accidents and ensure the safety of lives and property of coal mine workers，the fire causes，combustion characteristics，smoke flow characteristics，monitoring and early warning technologies，and prevention measures of mine belt conveyor fires were systematically analyzed. Then，further prospects were proposed based on the current research status. The results showed that the main causes of belt conveyor fire were friction temperature rise，electrical equipment failure，and open flame. There were some limitations for the tunnel fire model and corresponding numerical simulation parameters used to study the fire combustion and smoke flow characteristics of belt conveyors，the actual working conditions and environmental parameters of the transportation tunnel should be comprehensively considered. Although there were monitoring and early warning systems for belt conveyor fires in China，they had some limitations. It was necessary to introduce emerging technologies such as 5G，big data，and artificial intelligence，and combine them with hardware detection and personnel management to improve the coal mine belt conveyor fire prevention and control system，and then comprehensively promote the construction of safety and intelligent in coal mine.

In order to reduce the fire safety risk of urban buildings and improve the ability of building units to resist fire accidents，the influencing factors of fire safety were identified from three aspects: building fire protection design，building fire protection facilities and fire safety management，and the assessment index system of fire safety of urban buildings was constructed. A combined weighting-TOPSIS model of structural entropy and information entropy was applied to assess the fire safety risk of each district and each type of building in the cities. The model was validated with 262 buildings in 5 major areas of X city in western China. Finally，fire safety index and comprehensive ranking were obtained，and then the existing weak points of urban buildings fire protection were clarified. The results indicate that comprehensive evaluation order of fire safety is commercial complexes > primary and secondary schools > heritage buildings > high-rise buildings，city center > north of the city > east of the city > west of the city > south of the city. The fire safety risk of urban fringe counties and high-rises need to be paid attention to. The assessment results calculated with this model are consistent with the current situation.

To improve the synergistic explosion suppression and flame retardant efficiency of inert gas-water mist，based on spectral experiments，theoretical analysis and numerical simulation methods such as Fluent and CHEMKIN-PRO were used to study the changes in elementary reactions and typical free radical (H· and ·OH) molar fractions during the explosion suppression and flame retardant process of N₂ water mist at different injection positions and pressures. The results showed that staggered injection of N₂ and fine water mist had better synergistic explosion suppression and flame retardant effect than convection and parallel injections. For case of simulated pipeline，good explosion suppression and flame retardant effect were found only when the spray pressure of N₂ and water mist was 4.5 and 2 MPa，respectively. Furthermore，the maximum value of mole fraction for H· and ·OH was 0.006 4 and 0.006 9，respectively. The spray pressure can be applied to the actual methane explosion fire area based on scale effect. Moreover，the H· and ·OH mole fractions can be used as monitoring parameters during the operation of the current automatic fire extinguishing system in the fire protection area，and their changes can be used as a reference for fire extinguishing process.

In order to solve the problem that a large amount of multi-source heterogeneous structured and unstructured knowledge in the operation and management of cable crane is difficult to reuse，a large number of technical specifications，expert experience and other safety knowledge accumulated in the installation and operation and maintenance of cable crane were analyzed，and related entity classes of cable crane operation were extracted. A quintuple model was used to structurally express the safe operation of the ontology knowledge of the cable crane，and the binary relationship between classes was established. Then，the ontology expression language in Protégé was used to represent it programmatically. The ontology knowledge base of the cable crane entity，safety early warning and an emergency plan was constructed. 3D scene model of the cable crane was constructed using 3Dmax software，and then the model was imported into Unity3D engine. Knowledge retrieval of the ontology knowledge base was realized through user interface design and interaction functions in the engine. At the same time，based on the existing examples of faults and accidents，the corresponding emergency plans were associated with the hidden dangers existing in each entity of the cable crane. Finally，a complete 3D visualization platform for safe operation knowledge retrieval of cable cranes was constructed. The results show that all kinds of safe operation knowledge of cable-winch can be centrally and effectively managed by constructing an ontology knowledge base，and a knowledge retrieval platform combined with an ontology knowledge base can effectively realize efficient query and reuse of knowledge.

In order to study the evacuation of passengers in a train fire in a vacuum tube transportation system and the smoke spreading law，The fire numerical simulation software FDS and the personnel simulation evacuation software Pathfinder were used to study the evacuation of passengers in case of fire in a high-speed train compartment consisting of 5 cars in a low-vacuum tunnel. Comprehensively comparing the evacuation time，the degree of smoke spread and the CO concentration in 10 evacuation schemes，the best evacuation method for passengers was obtained，and a rescue vehicle was designed to assist evacuation by docking the door of the high-speed train. The results show that: when the passengers in the fire compartment are evacuated to the neighboring compartments，the best evacuation method for the passengers is to leave the two rows of passengers close to the doorway and the rows of passengers close to the fire source at the same time，and then evacuate the passengers row by row by the distance from the fire source from near to far. If the rescue vehicle is used to assist the rescue，when the fire occurs in compartment 1，compartment 2，or compartment 3，the total time to complete the evacuation of all passengers after the arrival of the rescue vehicle is 533，586，and 376 s，respectively. When a fire occurs in compartment 1，the utilization time of door 1 is 200 s; when a fire occurs in compartment 2，the utilization time of door 1 is 145 s; when a fire occurs in compartment 3，the utilization rate of the two doors is more balanced. Therefore，during the actual evacuation，passengers can be guided to fully utilize the two doors in the form of voice announcements to save the evacuation time. The research results can provide a reliable reference basis for the emergency rescue of passengers in future low vacuum tunnel train fires.

To improve the accuracy of miners' helmet-wearing recognition in coal mine underground operations，a helmet-wearing recognition algorithm was proposed based on human posture analysis and machine vision system optimization methods. First，Single Shot MultiBox Detector (SSD) was used as the basic model of multi-target identification. The squeezed neural network (SqueezeNet) was used to reduce the model parameters to develop an efficient recognition model，which improved the recognition accuracy of the miners' helmet and maintained the balance between the recognition accuracy and the calculation speed. Then，a multi-person posture estimation algorithm was used to locate the joint points of each miner and determine the miners' complex behavioral status. Finally，the upper limb nodes of the target were extracted based on fusion model of multi-target recognition and multi-person posture estimation，and then the helmet-wearing condition was determined by the spatial topological relationship between the upper limb nodes and the helmet frame. Moreover，3 000 pieces of image data were selected to validate the proposed method's performance. The results indicated that the machine vision system can optimize the hardware and software configuration to improve the system's performance. Furthermore，the identification accuracy reached up to 91.1%，which was much better than that of the latest helmet-wearing recognition algorithm. Therefore，the proposed system in this study can meet the requirements of helmet-wearing recognition accuracy for underground coal miners.

During the construction of underground extraction boreholes，trajectory deviation is common，prone to blind gas extraction areas and produces gas extraction blank zones. In order to ensure that gas extraction achieves the expected results，the 15121 bottom pumping lane，15124 low level lane and 15124 return air lane of Xinjing mine in Shanxi province were taken as the background of the project. We tested the deviation of borehole drilling through the seam and along the seam respectively，calculated the three-dimensional trajectory of the drill holes by using the mean angle full distance method，established the three-dimensional trajectory of the drill holes and the three-dimensional layer relationship of coal rock based on the geological information of coal seam assignment，realized the visualization of the trajectories of the drill holes，analyzed the factors affecting the deviation of the drill holes and the experimental fitting data，and came up with a characteristic of the deviation of the boreholes. The research findings suggest that cross-layer boreholes initially exhibit deviation within fine sandstone layers，with the deviation intensifying notably within the coal seam segment，reaching a maximum deviation of up to 0.52 meters within this section. In the case of in-seam drilling，greater drilling depth results in larger vertical deviations，with an average vertical offset of 1.37 meters at a depth of 40 meters when the opening angles of boreholes are similar. Overall，low-angle boreholes are more susceptible to gravity-induced deviations，leading to a higher likelihood of trajectory deflection，while high-angle boreholes tend to exhibit vertical deviations，albeit with a smaller overall deviation compared to low-angle boreholes. In the horizontal direction，borehole spacing is reduced by 0.68 meters for bottom drainage galleries，0.28 meters for lower position galleries，and 0.54 meters for return airways. The research results effectively guide the design of subsequent gas extraction drilling trajectories under the same geological conditions，provide theoretical support for controlling and eliminating the blind zone of gas extraction，and improve the efficiency and effectiveness of gas extraction.