DYNAMIC RESPONSE OF TUNNEL THROUGH MOUNTAIN UNDER THE INFLUENCE OF THE HOLE ELEVATION

When the mountain tunnel pass through the mountain and valley, the tunnel will inevitably be located on the slopes of different heights. Different hole elevation of the tunnel, the dynamic response under seismic load is bound to be different. Taking the loess tunnel of Western region as the engineering background, using the method of three-dimensional finite element numerical simulation, five different hole elevation model were set up(The pole elevation were h=0m, h=5m, h=10m, h=15m, and h=30m). In this paper, we explored the dynamic responses of the slope and the tunnel portal section under the influence of hole elevation. The results showed that:The change of the hole elevation has an important effect on the dynamic response of tunnel and slope. The displacement peak and peak stress of slope decreased with increasing hole elevation. The amplification effect is very obvious at the tunnel portal section, and the amplification effect is different by the affection of hole elevation. Obvious stress concentration phenomenon occurred on the slope near the entrance of the tunnel, and the dynamic response of acceleration and displacement of the tunnel invert showed that the hole elevation was larger, the length of amplification effect section was short. Therefore, the tunnel elevation effect should be considered in the seismic design of the crossing tunnel. According to the change of hole elevation of the tunnel, the anti-seismic fortified length and the key reinforcement area of the slope should be changed accordingly.