Study on Spraying Construction Method of a Non-Water Reacting Polymer Layer in the Tunnel

Non-water reacting double-component foamed polyurethane has been increasingly used in the field of transportation. Particularly, it is recognized that a polymer damping layer between tunnel linings and surrounding rocks can improve the seismic performance of tunnels. To facilitate the application of this polymer in tunnels, a spraying construction method of polymer damping layers was proposed. The polymer damping layer was prepared with hydraulic spraying equipment, and the construction process included the pre-treatment of the tunnel base surface, the pressure control of the spraying equipment, the adjustment of the spray gun working parameters and spraying quality control. In this paper, the effects of material ratio, material temperature, environmental factors (i.e., temperature, humidity and wind speed), spraying pressure and spray gun parameters (i.e., speed, distance from the sprayed surface and spray angle) on the layer formation were investigated. Thus, spraying parameters for better spraying performance were recommended. This study will provide technical support for polymer damping layer construction in the seismic design of tunnels.