Tunnel Fire Safety Performance Of The Lining Structure Study

For the ineluctability and high fatalness of tunnel fire accident, the research in tunnel fire has drawn great attention from academia and engineering department. Because the safety of tunnel liner is an important part of tunnel fire-resistant performance, the assessment of liner safety in tunnel fire has become an important task now.According to the fire cases and experiment results, the liner safety in tunnel fire is studied by the method combined with theory analysis and numerical simulation. Based on numerical analysis, the assessment system is established, and carried out using ANSYS according to the engineering case. The main conclusions are as follows:1) The high temperature load curve is studied out according to the distribution rule of smoke in tunnel fire, and the finite element method of temperature field is introduced to establish an integrated model combined with liner and wall rock. Then, on the basis of temperature field result, the stiffness of the highest temperature section is deduced, so as to ascertain the burnt degree of liner. The case simulation indicates that the burnt degree of vault is the most serious.2) The new method of liner intensity assessment is explored according to thermal-mechanical coupling theory: initial stress field analysisâ†'high temperature stress field analysisâ†'high temperature internal force fieldâ†'the check-calculation of safety factor. The thermal-mechanical coupling analysis should be done after the initial stress field analysis, and then internal force could be calculated through stress integral. The check-calculation of safety factor could be followed with the criterion of section in bonding or eccentric compression. The case simulation indicates that the vault is the weakness of the liner, and plastic deformation occurs seriously.3) Based on the stabilization theory of arch structure, the mathematical model is presented, and the nonlinear finite element buckling analysis method is proposed. A single-orientation hinge is supposed to simulate the plastic hinge of vault section, and the whole liner cross-section could be calculated according to the equivalent fire-resistant section. The load is applied step by step until the structure lost stability to get the buckling load. And then, according the buckling load with the internal force of liner structure in fire, the stability of liner structure is assessment.4) According to the assessment method of ground buildings, the assessment system of liner structure safety performance is proposed, which contains section stiffness, structure strength and structure stability. The system could provide reference for the engineering consultation or assessment and scientific research on the field of tunnel fire-resistant.