Research On Fire Smoke Movement Characteristic In Submarine Immersed Tunnel

Recently, the rapid development of submarine tunnel construction in China results in ventilation and disaster prevention problems which is one of the major difficulties restricting its development, especially large cross-section submarine tunnel. Meanwhile, several tunnel fire accidents worldwide show that although the fire is a small probability event, will bring great disaster. Therefore, the study of smoke movement mechanisms and personnel security expertise under the tunnel fire conditions in submarine tunnel is particularly urgent. This paper relys on the National Science and Technology Support Program " key technology research and demonstration on Hongkong-Zhuhai-Macao cross-sea bridge construction cluster" project five sub-topics four " key technologies on offshore immersed tube tunnel construction disaster prevention and mitigation", and is based on the background of the Hongkong-Zhuhai-Macao Bridge seabed immersed tube tunnel, research on the tunnel fire smoke spread characteristics and the personnel escape environment. The concrete works are as follows:1 Through analysis the tunnel fire smoke flow phenomenon mechanism, start from the energy conservation principle, set mathematical model of fire smoke. Through reasonable assumptions, the theoretical models about smoke temperature and velocity along the tunnel longitudinal attenuation are derived. Combine with the numerical simulation and full-scale test data, the rationality and reliability of theoretical models is verified. Finally, the spread properties of fire smoke in Hong Kong-Zhuhai-Macao immersed tube tunnel are obtained.2 Based on the background of the Hongkong-Zhuhai-Macao Bridge seabed immersed tube tunnel, according to the actual situation of the tunnel, set up the test tunnel of a length of 150m, and equip electromechanical systems and test measurement systems, create comprehensive test platform and test data acquisition software.3 Define the fire heat release rate of the oil tank fire and wood crib fire in the full-scale tunnel, and analyze the factors, propose on the design design scheme. Analysis focused on the combustion process and combustion phenomena of vehicle fires (cars and buses), and determine its HRR value and its influencing factors. The test of burning car in full-scale tunnel is the first time in the domestic, and foreign burn data of vehicles are also less, so accumulate valuable data for tunnel fire research.4 By developing full-scale tunnel fire tests, based on the determination of the fire combustion characteristics, analysis the variation of temperature and smoke field in the tunnel in-depth; determine the smoke spread characteristics parameters - the temperature, smoke layer height, speed and CO transport characteristics, in order to quantitative analyse the smoke flow state. Meanwhile, the smoke movement under each factor is also comprehensive analysed.5 According to the actual situation of the Hong Kong-Zhuhai-Macao Bridge immersed tube tunnel, using FDS fire simulation software to build three-dimensional numerical simulation model, and set reasonable boundary conditions. Simulate the different fire scenarios and improve the test which can not be taken into account, analyse the smoke flow in Hongkong-Zhuhai-Macao immersed tube tunnel. Focus on analyse the smoke distribution of the tunnel vault and sidewall, the critical wind speed and so on. The data provide strong support for the personnel and equipment safety and tunnel disaster prevention.6 Though analysis the hazards factors to human and personnel safe evacuation conditions in the fire scene, based on the tunnel fire, discuss the temporal and spatial distribution of hazards at the height of the personnel in depth. Around the differences of harmful hot smoke to human health and the scope of hazards, discuss hot smoke control mechanisms, and eventually propose personnel available safety evacuation time (TASET) under Hongkong-Zhuhai-Macao immersed tube tunnel fire. This will have vast importance to the assess of fire safety, and provide reference basis for proposing personnel escape strategy under the fire scene in Hongkong-Zhuhai-Macao Bridge immersed tube tunnel.