盾构掘进对单桩内力的动态影响

Dynamic influence of single pile internal force induced by adjacent shield driving

为了研究盾构掘进过程对周边桩基础内力的影响,结合苏州轻轨1号线玉山公园与苏州乐园盾构隧道区间的施工情况,采用三维有限元数值模型,研究盾构施工过程对单桩内力的动态影响.结果表明:在盾构施工过程中,侧桩的轴力均呈现桩顶和桩底处小、隧道轴线处最大的特点,侧桩的轴力和弯矩随盾构的不断逼近而变大,且最大负弯矩大于最大正弯矩;同时侧桩越长,桩身轴力也越大,不同长度侧桩的弯矩均在隧道轴线处最大.在盾构从正下方穿越单桩的施工过程中,桩身轴力均呈现中间小、两端大的特点,最大弯矩均出现在桩身中点附近.当盾构切削面到达正上方单桩时,桩变长后,桩身部分截面的轴力由压力变为拉力,桩身弯矩均在桩中点附近处达到最大值.

In order to research the influence on single pile internal force induced by adjacent shield driving,the numerical analysis was used to study the pile internal force by adjacent tunnel sheild costruction in Yusan Park and Suzhou Entertainment Resort on light-railway Line 1 of Suzhou.It showed that in the shield driving processes,the adjacent pile axis force was the characteristicly little at the pile top and end,and large at the tunnel axis zone.The adjacent pile axis force and the moment become larger and larger with shield approaching to adjacent pile,and maximal negative moment was greater than maximal positive moment;the longer the pile was,the greater the pile axis force was.The greatest moment of various lengthes adjacent piles was at the tunnel axis zone.When sheild crosses just right under the pile,the axis force was greater at pile top and end and little at the middle,the maximal moment is at the middle of the pile.When sheild cutting face arrived at the right above pile,the pile is pulled to be longer,the axis force of pile shaft section changed from compresive to tensile,and the maximal moment is at the middle of the pile with pile length elongated.