Study Of Smoke Prevention And Discharge For Laege Spcae Building On The Base Of Subway Transfer Station

The underground buildings with large space have been devloped largely in past decades years, which bring new challenge for the fire protection. Usuallly, subway station locates underground and it is a condensedly populated place underground building with large space. There are more difficulty for fire protection in a subway staion. Huge casualties and property losse are caused once a subway station catches fire. The smoke couldn't be fast and efficient excluded, which is the reason for huge casualties and property losse. Therefore, smoke controlling become a significant problem about fire safety. Small-scale experiment and complementary full-scale simulation are conducted with Fire Dynamics Simulator(FDS) software to study smoke prevention and discharge. The object of subway station is the administrative center station on Xi'an metro Line 2. The station includes four parts: a cross-shaped hall located in basement 1, platforms located in basement 2 and basement 3, respectively and a cylindrical dome on the ground and the area of the concourse and platforms are 3240m2 and 2520m2, respectively. The paper includes three parts as follows:The stairwell is often one of the main conduits for the spread of smoke. Once smoke spreads into the stairwell, it can migrate into the upper floor, which decreases visibility and is also very bad in an emergency. Thus, it is critical to prevent toxic smoke from spreading into stairwells. To solve the problem, the efficacy of smoke compartment between one-stream air curtain and hung wall is compared and it is found the air curtain is better to compart smoke. However, one-stream air curtain has some disadvantages and some improvement is proposed. The multi-stream vents and opposite vents are set at the air curtain, respectively and the different influence on the efficacy of smoke compart is researched.Once a fire accident takes place on the platform, the spread of smoke accelerate because of pressure difference among floors. To avoid the influence of negative pressure, the natural air makeup is joinded with mechanical ventilation. Three different mechanical ventilation modes are proposed. The first mode is that smoke is exhausted from basement 2, air supplied into basement 1 and basement 3, respectively(USMEBS). The second mode is that smoke is exhausted from basement 2(ME) and the third mode is that smoke is exhausted from basement 2, air supplied into basement 1(USME), respectively. Comparison among the ventilation modes is conducted and the best mode is found. The influences of vent layout, the volume of mechanical ventilation and so on are examinedHybrid ventilation integrates natural and mechanical ventilation components to create high efficacy and healthy ventilation system in a building. Hybrid ventilation is adopted to control the smoke once the station hall is on fire. Some modification about the setting parameters is adopted to achieve the best efficacy.The research provides a theory about the smoke prevention and discharge for the administrative center station on Xi'an metro Line 2 and some other under-construction stations.