Analysis Of Fire Scenacio And The Temperture Field Distribution Of Subway Interval Tunnel Segments

With the rapid urban construction, the subway has become an effective means to solve urban traffic pressure, while subway fire safety issues are also increasingly a cause for concern. Due to large passenger volumes and internal space relative close, once a fire occurs, it will cause serious casualties and property damage. When a metro shield tunnel fires, different fire scenarios can cause differences in the structure of the tunnel segments temperature distribution, thereby affecting the mechanical properties and damage assessment segments structure. How to create a suitable subway tunnel fire scenario, has a practical significance for the analysis of the tunnel fire temperature and structural safety assessment.Subway tunnel fire scenarios and associated distribution of temperature field are studied in the paper. The contents involve:design method of fire scenario and its influential factors; calculation theory and methods of section temperature field of the segments structure; analysis of the mechanical properties of the segments structure fires.Based on the case of countries in the subway tunnel fire research, combined with the standard temperature curve and the relevant benchmark curve, put forward for fire scenarios suitable for the subway tunnel, and the influencing factors should be reflected. Based on the theory of segment heat conduction, combined with finite difference method, calculation theory and methods of section transient temperature field of the segments structure are given. Through the fire test of one-third scale model segment, the regularity of temperature field of segment section is analyzed. Through proper selection of assumptions and thermal physical parameters and reasonable simplification of boundary conditions, the FEM software of SAFIR used successfully in simulating the transient thermal transmittance process of lining, by verified with test results of model segment. Based on calculation, analysis of different fire scenarios, segments thickness, cooling rate, overburden for the effects of tunnel segments temperature field, pointing out the main factors affecting the distribution of temperature field of the tunnel is the peak temperature and duration of fire. Through comparing the numerical analysis with reference to high-temperature test, changes of mechanical properties of shield tunnel segment under different thermal-mechanical conditions are studied. During the fire scenarios based on segment, because of non-uniform temperature distribution of segment section and deterioration of segment material, resulting in deformation of the segment, deflection increases, stress change significantly.In this paper, combining numerical simulation software of SAFIR and test of segment structure fire, the distributions of temperature field metro shield tunnel are studied, and provide a foundation for further research of tunnel segment structure property.