Evaluation on the Effect of Foam Concrete Damping Layer in Highway Tunnel
Foam concrete materials have gradually been promoted and applied in tunnel seismic isola-tion layers due to their excellent seismic performance.This study analyzed the seismic isolation mech-anism of foam concrete seismic isolation layers in highway tunnels under strong earthquake actions.A refined tunnel structural model was established by ABAQUS finite element software,wherein the foam concrete seismic isolation layer adopted a compressible foam constitutive model to characterize the compressive behavior of foam concrete,used to analyze the damage to the secondary lining structure of the tunnel under strong earthquake actions.The results indicate that the damage to the tunnel structure under the combined action of horizontal and vertical seismic loads is more severe than when subjected to horizontal loads alone.Although the foam concrete seismic isolation layer cannot fundamentally change the stress state of the tunnel structure,it can significantly reduce the internal force amplitude of the secondary lining.Furthermore,a comparison of the seismic isolation effects of foam concrete seismic isolation layers of different thicknesses reveals that for highway tunnels traversing high-intensity earthquake zones,the most effective seismic isolation is achieved when using a foam concrete seismic isolation layer with a thickness of 0.4 m under strong earthquake actions.