盾构开挖对邻近桩基影响的试验研究

Experimental study on the influence of shield excavation on adjacent pile foundation

邻近桩基础受到盾构开挖扰动时,桩身会产生附加的应力和位移,从而对桩基承载力造成不利的影响。针对盾构开挖对临近桩基受力影响的研究,可为地下工程的安全稳定施工提供参考依据。文章采用室内模型试验的研究方法,分析了在隧道与桩基相对位置和桩体长度不同情况下桩顶的竖向位移和桩身内力,研究了盾构开挖对邻近桩基的影响。结果表明:隧道开挖导致的桩顶竖向位移和倾斜率均随隧道距离增加而变大,且桩长越短所受影响越明显;桩身附加弯矩的变化随隧道距离增加影响减小,距离隧道越远正弯矩区域越接近顶端,且桩长较短时桩身产生负弯矩区域越大;桩身的附加轴力会随桩侧摩阻力的减少而增加,且后桩由于前桩的隔离作用而使附加轴力增加较小。

When the adjacent pile foundation is disturbed,the pile body will generate additional stress and displacement,which will adversely affect the bearing capacity of the pile foundation.The study about the influence of shield excavation on the adjacent pile foundation can provide a reference for the safe and stable construction of underground engineering.In this paper,through laboratory model tests,the vertical displacement of the pile top and the internal force of the pile body are analyzed when the relative position of the tunnel and pile foundation and the pile length are within a certain range.The results show that the vertical displacement and inclination rate of the pile top caused by tunnel excavation increase with the increasing of the tunnel distance.The shorter the pile body,the more obvious the impact force.As the tunnel distance increases,the change in the additional bending moment of the pile body decreases.The farther away from the tunnel,the closer the positive bending moment area to the top,the shorter the pile length,the greater the negative bending moment area of the pile body.The additional axial force of the pile body will increase as the lateral friction resistance of the pile decreases.The additional axial force of the front pile’s isolation effect will increase less.