深基坑开挖对既有隧道的影响研究

A Study on the Influence of Deep Excavation on the Existing Tunnel

使用plaxis二维有限元软件模拟隧道附近的深基坑开挖,研究深基坑开挖对既有隧道的影响。结果显示,随着基坑的开挖,最大水平位移不断增大,且最大水平位移发生在基坑开挖面以下、地下连续墙附近;基坑外侧土体发生沉降,内侧土体发生上浮;土体最大沉降点从地下连续墙逐渐向隧道上方移动;隧道上方地面的竖向位移比水平位移大;隧道顶和隧道底的水平位移相差不大,而隧道底的竖向位移比隧道顶小;离基坑较远一侧和较近一侧的竖向位移相差不大,而离隧道较近一侧的水平位移比较远一侧大;地下连续墙的深层水平位移逐渐变大,且最大水平位移发生在坑底以下5~7 m。

The plaxis 2D finite element software is used to simulate the deep excavation near a tunnel and the influence of deep excavation on the existing tunnel is studied.The result shows that as the excavation proceeds,the maximum horizontal displacement increases,and the maximum horizontal displacement is in the soil which is under the excavation surface and near the underground diaphragm wall.The soil outside the foundation pit settles and the soil inside the foundation pit floats upwards.As the excavation proceeds,the maximum settlement point moves from the underground diaphragm wall to the soil above the tunnel.The settlement of the ground above the tunnel is larger than the horizontal displacement.The horizontal displacements of the top and the bottom of the tunnel are close while the settlement of the bottom of the tunnel is smaller than that of the top of the tunnel.The settlements of the far side and the near side of the tunnel are close while the horizontal displacement of the near side of the tunnel is larger than that of the far side of the tunnel.The deep horizontal displacement of the underground diaphragm wall increases as the excavation proceeds and the maximum horizontal displacement happens 5~7 meters below the excavation surface.