Tunnel construction projects in China have developed rapidly，and significant dust hazards are associated with drilling and blasting construction. To improve the effectiveness of spraying to reduce dust in tunnels，this article uses digital simulation and a tunnel model was created using ANSYS. The variations in dust mass concentration distribution under different conditions，such as surrounding rock temperature，jet velocity，and nozzle diameter，were investigated in the study. The results show that as the surrounding rock temperature increases，dust movement becomes more intense，which significantly affects dust reduction efficiency. The dust capture effect of atomized water droplets decreases with the increase in surrounding rock temperature. With the increase of water jet velocity，the water pressure in the jet pipe increases，improving the dust capture effect of the droplets. Dust reduction efficiency decreases with increasing nozzle diameter. When the nozzle diameter is too large，the ability of water mist to capture particles weakens. Conversely，a smaller nozzle diameter improves dust reduction efficiency. However，if the nozzle diameter is too small，too much splash water spray rather than affect the efficiency of the dust.

In order to study the effect of liquid CO₂ injection on coal spontaneous combustion heat production and gas release in the gob with high gas content and easy spontaneous combustion，the gas desorption test system was composed of a self-made variable temperature chamber and desorption instrument to simulate the influence of liquid CO₂ injected into a high-temperature point of gob on coal sample temperature and coal gas desorption amount and analyze the change of gas desorption energy of coal sample under corresponding coal body gas pressure and different temperature during the process of "falling to rising" temperature change. The results show that the temperature of the coal sample will stabilize at a lower level，and the gas will stop desorbing within 60 minutes to 100 minutes after the liquid CO₂ is injected. After 100 minutes，the cold energy gradually runs out，and the coal continues to oxidize and heat up，and the gas resumes desorbing with an increasing desorption rate. The cold energy released by the liquefied CO₂ gasification and the CO₂ gas has an excellent inhibitory effect on reducing coal temperature and gas desorption. When the coal sample temperature is between 10 and 30 ℃，the coal is in a low energy state. In this temperature range，the internal coal is more likely to cause the adsorption heat value to stabilize. The decrease in the surface free energy of the coal body will also present a stable trend.

In order to reveal the sloshing behavior of vehicle-mounted liquid hydrogen storage tanks and improve their transportation stability，a numerical simulation model of vehicle-mounted liquid hydrogen storage tank sloshing was established. The impact of liquid hydrogen fluid sloshing on the storage tank during braking and turning was studied. The effects of driving speed，longitudinal and lateral acceleration and filling rate on the sloshing behavior of liquid hydrogen in the storage tank were discussed，and a wave-proof plate was designed to suppress the sloshing of liquid hydrogen. The results show that the stable driving speed of the vehicle has little effect on the liquid hydrogen sloshing in the tank. The more urgent the vehicle brakes or turns，the more severe the liquid hydrogen sloshing in the tank，the more serious the impact on the tank，and the longer the time required for the liquid hydrogen to reach a stable state. The closer the filling rate is to 50%，the more severe the sloshing is. As the filling rate increases to 90%，the impact of liquid hydrogen on the storage tank is more significant. However，the higher filling rate reduces the liquid hydrogen movement space and makes the sloshing amplitude more gentle. The anti-wave plate in the tank can effectively separate the liquid hydrogen sloshing space，so that the maximum longitudinal impact force of the tank is reduced by 9.6% and 17.5%，and the maximum lateral impact force is reduced by 34.6%，which significantly reduces the impact on the tank and shortens the liquid hydrogen recovery time.

In view of the difficulties in obtaining instability data of open-pit mine dump and the small amount of sample data，a discrimination model of slope stability state of open-pit mine dump based on migration learning algorithm was proposed. According to the actual geological conditions and rainfall conditions of the dump slope of F open-pit mine in Shaanxi Province，a similar simulation test scheme of slope with different soil-rock mixing ratio was designed under the condition of rainfall. The data of water content，earth pressure and pore water pressure of the slope model were collected and processed. Considering the influence of small sample data set on the classification accuracy of GBDT model，using the idea of transfer learning，the sample weight of source domain data set and target domain data set was iteratively updated by TrAdaBoost algorithm，and the GBDT model was used as the weak learner for data sample training. Finally，according to the classification result of the weak learner，the weighted majority voting method was used to generate a TrAdaBoost-GBDT dump slope stability discrimination model based on transfer learning to improve the discrimination accuracy of small sample data label categories. The results show that the proposed dump slope stability state discrimination model has a better performance in judging the stable state than other algorithm models，and the values of accuracy，precision，recall and area under curve(AUC) are 93.3%，87.5%，100% and 93.8%，respectively. Compared with other algorithm models，this model can improve the accuracy of slope stability discrimination of small sample data sets，and make up for the low accuracy of machine learning classification results of small sample data sets.

In order to better use microwave antireflection technology to safely and efficiently extract coal seam gas，and to explore the influence of coal moisture content change on the antireflection effect under cyclic microwave conditions，firstly，the transverse relaxation time (T₂) spectrum and longitudinal relaxation time (T₁) -T₂ spectrum characterizing the pore structure characteristics of coal samples were obtained by NMR technology. Then，the characteristic parameters of nuclear magnetic resonance were obtained by using T₂ data，and the change of pore structure evolution with water content under cyclic microwave radiation was further clarified. Finally，based on the mechanism of cyclic microwave permeability enhancement，the pore structure evolution mechanism of different water-bearing coal bodies was revealed. The results show that the pore structure of coal with different water saturation is obviously improved under cyclic microwave radiation，and the coal sample with 75% water saturation has a better antireflection effect than other test coal samples. In the process of cyclic microwave radiation promoting the evolution of pores to larger pores，pore blockage occurs due to the thermal fracture of coal，and increasing water saturation can reduce this phenomenon. The cyclic microwave anti-reflection mainly relies on thermal stress and air pressure. With the improvement of coal permeability，the effect of microwave anti-reflection is weakened，and the influence of coal water content is weakened.

To investigate the evolution of overburden structure and the stability of district coal pillars during the mining of shallow-buried coal seam island faces，a study was conducted with the 50104 working face of Taihua coal mine as the engineering background. The research employed a combination of theoretical analysis，numerical simulation，and on-site measurement to analyze the load-bearing capacity of the district coal pillars and the characteristics of overburden structure evolution on both sides. The FLAC^3D numerical software was utilized to simulate the distribution of plastic zones and the evolution of mining-induced stress. The results indicate that during the advancement of the 50104 working face，the plastic destruction of the district coal pillars on both sides lagged behind the progress of the working face. The district coal pillars located in the goaf area behind the working face were in a state of plastic destruction，while those in front of the working face coal wall maintained a stable elastic zone，overall remaining stable. Throughout the working face advancement，the stress distribution of the district coal pillars on both sides exhibited the same characteristics，with two 11 m coal pillars showing symmetric high-stress concentration areas，both located behind the working face. The development speed of the high-stress destruction area of the district coal pillars lagged behind the advancement speed of the working face. The average stress value in the central area of the district coal pillars in front of the working face increased from 3.35 MPa to 3.54 MPa，but it never exceeded the coal pillar bearing capacity value calculated theoretically. Analysis of the mine pressure monitoring data from the 50104 working face revealed that the average initial support force was 3 932.4 kN，accounting for 55% of the rated initial support force of hydraulic support. The average maximum working resistance was 5 812.3 kN，representing 61.2% of the rated working resistance. The weighted average resistance was 4 836.6 kN per support，which is 50.9% of the rated working resistance. The maximum pressure was 6 013 kN，with a support stress of about 2.35 MPa，proving the stability of 11 m coal pillars and indicating that the overall stability of the district coal pillars in front of the working face coal wall is relatively good.

To understand the characteristics of goaf air leakage and gas migration in different mining periods of Y-type ventilation working face without coal pillar mining，97312 working face in Sihe No.2 coal mine of Jinneng Holding Equipment Manufacturing Group Co.，Ltd. was selected. The sulfur hexafluoride (SF₆) tracer gas approach was used to determine the air leakage area distribution，air leakage type，and air leakage volume of 97312 working face and the roadways under different connectivity states with the adjacent 97311 working face goaf. The air leakage flow field distribution and gas migration characteristics in the goaf area were analyzed by numerical simulation. The results showed that 97312 working face had four air leakage areas of positive pressure-negative pressure-positive pressure-negative pressure along the wind direction. The main air intake roadway 97222 had positive pressure leakage. The air return roadway 97224 had mainly negative pressure air leakage along the gob-side entry retaining section，but positive pressure leakage was prone to occur near the extraction pipe and in the area where the roadway was severely deformed. After connectivity with the adjacent goaf area，an additional air leakage path was created. Moreover，the connection status with the adjacent goaf affected the internal air leakage flow field and gas migration of the goaf. Air leakage from the 97311 goaf area carried gas to the 97312 goaf，causing an increase in gas volume fraction in the 97312 goaf，working face，and the gob-side entry retaining section of the 97224 roadway. After the closure of the 97311 working face，the gas volume fraction near the connected goaf area decreased.

In order to improve the safety of the shale oil gathering and transportation process，this paper took the shale oil gathering and transportation process under the in-situ transformation technology of superheated steam injection of oil shale as the evaluation object. In the process of shale oil gathering and transportation，the hazard were analyzed and the whole process was divided into three subsystems. The risk of each subsystem was analyzed qualitatively by using hazard and operability analysis(HAZOP) method. According to the results of the qualitative analysis，the probability of fire and explosion accidents and the risk grade of each subsystem were calculated by using layer of protection analysis(LOPA) and Dow fire and explosion index(F&EI) method. The nodes of shale oil gathering and transportation process were divided，and Bow-tie models for oil and gas leakage accidents containing hydrogen sulfide and oil and gas leakage accidents after purification were established respectively. Based on results of risk assessment，effective safety prevention and control measures were developed. The results show that the subsystems that may cause accidents in the oil and gas gathering and transportation process are: steam generation system，cooling separation system，ammonia desulfurization system and cooling separation system，in which the leakage of the steam generation system will not cause fire and explosion accidents，and the fire and explosion risk grades of the remaining subsystems are: ammonia desulfurization system，cooling separation system and gas extraction and desulfurization system in order from heavy to light.

Physical evidence investigation was a necessary means and important link to identify the causes of hazardous chemical incidents. However，the manifestations of hazardous chemical incidents were often explosions and fires，which could easily trigger a domino effect，making physical evidence investigation somewhat difficult. In order to improve the efficiency of on-site inspections and reduce the occurrence of hazardous chemical incidents. MFA method was adopted to conduct on-site intelligence information analysis and explore the application value of MFA theoretical methods in the physical evidence inspection of hazardous chemical incidents based on specific cases. Based on "Jiangsu Xiangshui 3·21 serious Explosion Accident"，"Material Flow Analysis Map" and "Hazardous Substance Distribution Map" were drawn for Tianjiayi Chemical Plant，and material flow analysis research was conducted on the involved enterprises. The results indicate that MFA can identify hazardous areas and substances，providing safety protection reference information for on-site inspectors. It can also provide scope and direction for extracting，inspecting，and identifying on-site physical evidence.

In order to ensure the normal operation of the low-background experimental chamber and prevent structural collapse，a structural safety analysis was conducted using Abaqus software. Initially，a simplified model of the experimental chamber was established based on the finite element method. This was followed by static load response analysis under extreme conditions，seismic load response simulations，and buckling analyses. Finally，the stress response and buckling critical loads of the oxygen-free copper sections with varying thicknesses were calculated to determine the permissible limit wall thickness of the experimental chamber. The results indicated that，under static pressure，the weakest regions of the chamber were the top of the oxygen-free copper section and the transition area of the circular end cap，with a critical buckling load of 0.307 MPa and a permissible limit wall thickness of 5.1 mm.