Long Highway Tunnel Exhaust Corbel Resistance To Fire Performance

As the increasing of extra-long highway tunnels, the tunnel ventilation and smoke exhaust in fire had been paid more and more attentions. In developed countries, the mode of tunnel ventilation and smoke exhaust changed from vertical to central, and the latter was used widely in these countries. Fire would damage the framework of tunnel ventilation and smoke exhaust seriously and threaten the security of travelling, but there wasn't any researching in fire resistance and key parameter in high temperature in our country so far. During the introducing of this technology, it turned into an important problem that how to estimate and improve the security of the framework of ventilation and smoke exhaust in extra-long highway tunnels.Corbel connected roof clapboard with secondary lining in the framework of ventilation and smoke exhaust, playing role in joining each component and transferring loads. So, researching in security of corbel is the base of fire resistance study in the whole framework of ventilation and smoke exhaust. This dissertation planned to use the experimentation of full-scale components and numerical simulation to research the fire resistance and key parameter of smoke shaft corbel. The main work was as following:(1) The dissertation summarized the thermal parameters and the mechanical properties of steel and concrete in fire (and after fire) at home and abroad. The appropriate parameters were chose by ANSYS calculation. It laid a foundation for the numerical simulation.(2) Full-scale smoke shaft corbel component tests were carried out using large-scale fire test furnace. The temperature field distribution law of inserted steel bars section and concrete section under HC standard curve was obtained, and the failure law of corbel was also obtained.(3) The protective effect on corbel of fire retardant coatings was researched by comparative tests between non-fire retardant coatings components and fire retardant coatings components. And the residual bearing capacity of corbel after fire was studied by bearing capacity comparative between unfired components and components after fire.(4) The key parameters of inserted bar glue in corbel components in fire were tested, the fire safety of inserted bar glue was researched.(5) Based on the tests, the numerical simulation of temperature field in smoke shaft components in fire and its bearing capacity after fire was carried out by finite element analysis software ANSYS. The simulation results were compared with the test results, so that to discuss the feasibility of numerical simulation in the fire-resistant research on smoke shaft corbel.The test data and laws obtained from the research can prefer a reference to the further study on fire resistance and fire response of smoke shaft structure in extra-long tunnel and the fire-resistant design. The paper has great theoretical and practical significance to fire-resistant research on extra-long tunnel.