4.3 Test scheme

In Table.2, the case 2 and 3 are to study the effect of the shock absorption layer. The polyethylene material that is adopted to the shock absorption layer circumfuses the outside surface of the tunnel lining (the invert is not laid).

Table.2 Test conditions of mountain tunnel model

5 Model test results and analysis

5.1 Strain response analysis of tunnel structure

There are more than 30 strain gauges at the key positions, thus the strain response law of the tunnel lining is obtained by the strain gauges.

In Figure.3, when the acceleration 0.4g(equivalent to degrees) is input from shaking table, the maximum strain amplitude value of the vault is 22με in the case 2, while the case 3 is for 6.5με, thus the strain amplitude value is obviously decreased after the shock absorption measure is taken. The maximum strain amplitude value of the invert do not change because the shock absorption layer is not set at the right tunnel invert. So it is obvious for the damping effect that the shock absorption measures are taken for tunnel structure at the tunnel portal.

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