A Study on Composite Tunnel Fire-retardant Coating and Its Performance
|Keywords||The Tunnel Fire-retardant Coating Fire Resistance Bond Strength Optimal Formulation Finite Element Analysis|
Tunnel fire-retardant coating has become an effective measure of tunnelstructure fire protection due to poor performance, low cost, convenientconstruction.However, the fire resistant, bond strength and other performance remainsto be perfect.because the tunnel fire-retardant coating research and development andapplication are late. How to further improve the fire resistance, adhesive strength andother performance of tunnel fire-retardant coating is the emphasis and difficulties incurrent tunnel structure fire protection research.Thus, This paper analyzes the flame retardant mechanism of fire-retardant coating,selects the appropriate experimental materials, tests and optimizes many t imes to theproportion of composite binder, the ratio of inorganic heat insulation fillers, foamingmaterials, and the proportion of auxiliaries, explores the impact of the changes ofvarious components on the properties of fire-retardant coating, finally determines thebest dosage of the tunnel fire protection coating components, and developed thetunnel fire-retardant coating, which.good fire resistance, good water resistance,freeze resistance and acid-proof alkaline, high bond strength, high flexibility. Inaddition, with the aid of the finite element analysis software ANSYS，this papercalculates the tunnel temperature field under the hydrocarbon fire heating condition,and analyzes the impact of the tunnel fire-retardant coating tunnel on the tunneltemperature field in the fire cases.The test results show that the tunnel fire-retardant coating has good fireresistance, which can effectively prevent heat from transmitting to the tunnel inside inthe high temperature condition；The impact of all factors on tunnel fire-retardantcoating’s fire resistance from primary to secondary order is: composite binder>foaming materials> inorganic heat insulation fillers； According to the optimalformulation, the coating’s fire resistant can achieve185min when the coatingthickness is20mm and it has excellent fire resistance and good physical and chemicalproperties, which achieves the expectant purposes; Meanwhile, Compared with theexisting tunnel fire-retardant coating, the coating’s fire resistance is stronger, thebonding strength is higher, the dry density is less, the drying time is relatively shortand has good practical value.In addition, by using finite element software ANSYS, the tunnel temperature field under the action of the hydrocarbon heating conditions of calculation show thatthe heating rate of all nodes without the tunnel fire protection is very fast in the firecases, and the closer the tunnel surface node, temperature curve shape is closer tohydrocarbon curve; Along the tunnel thickness, the node temperature is graduallydecreasing, the temperature gradient is higher if it closer away from the fire surfaceand the temperature gradient is less if it far away form the fire surface. The fire has agreater influence near the place rock and lining structure at the bottom of the placeand Lining structure of arc and straight lineExperimental research and finite element analysis show that the tunnelfire-retardant coating can effectively prevent heat transmitting to the concrete, slowdown the tunnel temperature rise, greatly improve the fire resistance of components.Therefore, the tunnel fire-retardant coating for tunnel fire protection layer to consideris feasible when we carries on the tunnel fire protection design.