隧道开挖引起的单桩竖向极限承载力变化研究

城市隧道开挖不可避免导致建筑物基桩承载力的变化.本文利用ANSYS建立弹塑性有限元模型,在考虑桩端位于隧洞水平轴线上方、与隧洞水平轴线平齐、位于隧洞水平轴线以下3种情况及桩洞相对位置不同的情况下,对开挖后单桩竖向极限承载力变化进行了数值研究,数值仿真实验结果表明：在桩洞相对水平距离一定的情况下,当桩端与隧道水平轴线平齐时,承载力变化率最大,属较危险桩长;当桩洞相对水平距离在1.5倍隧洞直径与2倍隧洞直径之间时,单桩竖向极限承载力变化率最大,属承载力变化敏感区.

Numerical Simulation Research on Change of Vertical Ultimate Bearing Capacity of Piles Due to Tunneling

Tunnelling can cause the change of bearing capacity of pile inevitably.An elastoplastic FEM computational model is established via ANSYS,which is used to research the change of ultimate bearing capacity of pile after tunneling in the following three typical locations: the pile tip above the tunnel axis;on the tunnel axis;below the tunnel axis.The pile bearing capacity varying with the lateral distance away from the tunnel axis is also researched.The rsults of the numerical simulation analysis show that the pile ultimate bearing capacity changes most as pile tip on the tuunel axis for the fixed lateral distance of pile and tunnel,which is the most dangerous pile length.The pile vertical ultimate bearing capacity changes most when the relative lateral distance varies between 1.5 times tunnel diameter and 2 times tunnel diameter,which is in the sensitive zone.