Study On Fire-resistance Performance Of Single-channel Fire Immersed Tunnel

In this paper,a full-scale model of Hong Kong-Zhuhai-Macau immersed tunnel containing steel bars was established by the finite element software ABAQUS,and the fire resistance performance of the immersed tunnel under the unilateral channel fire in the immersed tunnel was studied and analyzed.The main research contents and conclusions are as follows:(1)The research results on the performance parameters of steel and concrete at home and abroad were collected and summarized,and the thermal and mechanical properties of steel and concrete in various countries were compared and analyzed by numerical simulation and experimental verification methods.In the analysis,it was found that the thermal performance and mechanical properties of reinforced concrete and concrete specified by Canadian scholar T.T.Lie can better reflect the fire resistance of reinforced concrete structures.(2)The temperature of the main structure was selected from a fire test of the immersed tunnel to conduct research and analysis.Then based on the experimental conditions,using the finite element software ABAQUS to numerically analyze the temperature field of the immersed tunnel physical engineering,and numerically simulate the temperature of the steel and concrete and the temperature in the test.It was found that due to concrete bursting during the test,the temperature of the steel and concrete in the test was greater than the numerical simulation;in addition,in the fire test of the immersed tunnel,the protective measures using a layer of 1cm thick fireproof sheet plus 1.2cm thick fire retardant coating can be effective to hinder the transfer of heat.(3)The temperature field and mechanical properties of the immersed tunnel without fire protection material were analyzed numerically under the HC curve,and compared with the fire resistance of the immersed tunnel protected by the fire protection material under the HC curve.The results show that in terms of temperature,compared with the immersed tunnels protected by fireproof materials,the internal temperature gradient and heating rate of the immersed tunnels without fire protection measures are larger;In terms of mechanical properties,immersed tunnel tunnels protected by fire protection do not exhibit high material degradation at high temperatures,they have more structural deformation,and the bearing capacity of the structure is smaller.Among them,the material properties of steel bars are most severely affected by high temperatures,and steel bars closer to the fire surface have basically lost bearing capacity when their temperature reaches 600°C.(4)The numerical analysis compares the fire resistance performance of the immersed tunnel tunnel protected by fireproof materials under two typical tunnel fire scenarios(ie,RABT/ZTV curve and HC curve).The results show that the immersed tube tunnels in both fire scenarios are similar in terms of temperature field distribution and mechanical properties.