基于三维有限元程序ABAQUS,分析由于隧道开挖引起的不同位置处的桩基水平位移及桩头沉降特性,数值模拟结果表明:由于隧道的开挖,桩身上部会产生往隧道侧移动的变形,而在桩身底部会产生反方向的位移,从而在桩身上形成P—Δ 效应;桩头沉降值及桩身最大水平位移随着桩—隧水平距离的增大逐渐减小,当隧道开挖中心位于桩底处时,允许的最小安全桩—隧水平距离S大致为2倍隧道直径D;隧道轴线处于桩基上部时有利于减小桩基附加变形,当桩—隧水平距离S=1.5D时,允许的最小安全桩—隧竖向距离H大致为0.5D.%Based on three dimensional finite element program ABAQUS, the settlement and lateral deformation of existing pile foundation with different pile-tunnel distance induced by tunnel is analyzed, and the numerical results show that: the top part of the pile foundation will move toward the tunnel while the bottom part will move toward the opposite side, thus the P-Δ effect occurring on the pile foundation; pile settlement and maximum lateral deformation are decreased with the increasing of pile-tunnel horizontal distance, and the allowable minimum pile-tunnel horizontal distance is approximate 2 times of the tunnel diameter D when the axis of the tunnel is located at the bottom of the pile foundation; additional deformation will be minished when the axis of the tunnel is above the pile base, and the and the allowable minimum pile-tunnel vertical distance is about 0.5D when the horizontal distance of tunnel-pile is 1.5D.
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