Research On The Smoke Diffusion Law And Prevention And Control Of Fire In Large Rectangular Underground Cavern

This article focuses on the topic of underground cavern fires,taking the underground powerhouse of Xiaowan Hydropower Station as the research object,and studies the fire risk,fire smoke diffusion,and prevention and control during the operation and maintenance period of underground caverns.As the main body of hydroelectric engineering,the underground cavern group has many fire hazards due to its large cross-section,narrow channels,dense lines,and difficult ventilation.When a fire occurs,smoke spreads quickly,and the proportion of casualties caused by smoke is the highest in the fire scene.Therefore,a comprehensive evaluation of the fire risk situation in underground caverns of hydropower projects,further understanding of the smoke diffusion law in large cross-section caverns,and exploring and developing prevention and control strategies suitable for corresponding scenarios based on their movement characteristics are the key and difficult points of current safety management in hydropower projects.This article uses theoretical analysis and numerical simulation to conduct research,obtaining the risk levels of the main locations of underground caverns,exploring the diffusion law of fire smoke in the main factory building,and proposing corresponding prevention and control measures.The main research content and achievements are as follows:(1)A fire risk assessment model for underground caverns of hydropower stations was established based on set pair analysis theory,and the main locations were evaluated.The results showed that the fire risk level of the auxiliary powerhouse,busbar tunnel,and main transformer tunnel in the underground caverns was medium,while the main powerhouse was a high-risk area.(2)Numerical simulation was used to explore the diffusion law of smoke in the main factory building.Temperature,flow rate,and shading rate were selected as the main research parameters,and the development process of smoke during a fire was obtained.The changes in the main smoke parameters at different stages were analyzed.The results show that the temperature of the flue gas decreases with the increase of the distance from the ignition source,the flow rate is faster at the lower edge of the ceiling,and the variation pattern of the shading rate is more complex,with the final value approaching 100%.(3)Several smoke prevention and control modes were proposed and simulated,with smoke blocking vertical walls,smoke exhaust outlets,and smoke exhaust ducts as the main facilities.The results show that the independent use of smoke blocking vertical walls has poor smoke control effects,while the modes of "smoke blocking vertical walls+ mechanical smoke exhaust" and "flue + mechanical smoke exhaust" have good smoke control effects,and can be used as the main smoke control method for underground tunnels.From the perspective of applicable scenarios and difficulty in construction and maintenance,each mode has its own advantages and disadvantages.