Abstract: Dynamic strength reduction method was used in the seismic stability numerical analysis for hydraulic tunnel. Shaking table test modelling the effect of earthquake on tunnel was conducted to verify the result of numerical analysis. The test result were consistent with that of the numerical analysis. The results suggest that the destruction of the tunnel is a gradual process. First, damage zone appears at weak parts and then gradually expands until it penetrates through. The seismic failure modes are different when the tunnel depth is different: for shallow tunnel, the damage zone forms above the tunnel and penetrates to the ground; whereas for deep tunnel, the damage zone forms around the tunnel, and does not extend to the ground. Tunnel diameter has great impact on the dynamic stability of the tunnel. As the tunnel diameter doubles, the safety factor reduces by about 45%.

Key words: hydraulic tunnel, dynamic strength reduction method, earthquake, depth, shaking table test