Damping effects of different shock absorbing materials for tunnel under seismic loadings

Abstract

Circular tunnels are widely used in infrastructure. Under the action of earthquakes, the destruction of circular tunnels will result in a large number of economic losses and casualties. Therefore, the study on shock absorption of tunnels is important. However, the research has not been sufficient on the effect of the damping layer on seismic response of a circular tunnel in sand. In this paper, the influence of the damping layer on the seismic response characteristics of circular tunnels in sand is studied by large-scale shaking table test. The actual El-centro wave is loaded to the model system in three directions during the tests. The input peak seismic acceleration values are 0.05 g, 0.1 g and 0.2 g. Then the effects of two different damping materials on the dynamic response characteristics of circular tunnels are analysed quantitatively. The test results show that the damping layer reduces the seismic response of the circular tunnel. The response accelerations of the tunnel bottom and crown without damping layer are greater than that with the damping layer, which indicates that damping layer absorbs the energy caused by the seismic motion. When the sponge rubber is used, the circular tunnel dynamic response is more attenuated than that with foam board. In conclusion, the shock absorbing layer can effectively reduce the seismic response of tunnel. As a result, the damage of the tunnel decreases under the earthquake. This study has clarified the isolation mechanism of the shock absorbing materials. It is recommended to use sponge rubber material as the shock absorbing layer.