Experimental study on fireproof board insulation technique for steel-concrete-steel immersed tunnel

Fireproof board insulation schemes applicable to steel-concrete-steel immersed tunnel elements were proposed, and then the thermal insulation effect of those schemes was examined by conducting fire tests under RABT standard fire curve, and the influence of the thickness, the material, the installation method and joint treatment method of fireproof boards on thermal insulation effect was discussed. It is found that fireproof boards can be fixed on the surface of the steel shell through keel and angle lifting, and it can play an obvious fire insulation effect in the fire. The thicker the fireproof board, the more obvious the effect of thermal insulation, the maximum temperature of steel shell has quadratic relationships with the thickness of fireproof boards. Thermal insulation effect of calcium silicate fireproof boards is slightly better than vermiculite fireproof boards. After the fire, vermiculite fireproof boards are more complete and do not cause obvious corrosion to the steel shell, calcium silicate fireproof boards warps, breaks, and is easier to fall, and causes corrosion to the steel shell. Vertical joints, L-type joints and double-layered boards staggered joints, which sealed with expansive fireproof sealant, can effectively stop the hot smoke of fire.