地铁隧道盾构施工对桩箱建筑物影响研究

为保证地铁双线盾构隧道下穿桩箱基础建筑的安全,采用abaqus有限元软件建立计算模型,模拟不同桩长、桩径、土体损失率及不同工况下桩基和基础底板附加变形及附加内力变化规律,从而对隧道下穿桩箱基础建筑的设计提供借鉴作用。结果表明:(1)随桩长增加,底板竖向附加变形和附加弯矩逐渐变小,底板竖向附加弯矩在桩顶出现极大值;3号基桩(右线隧道左侧)随桩长增加,桩身最大水平位移、附加弯矩和附加轴力均逐渐减小。(2)随桩径增大,底板竖向附加变形逐渐减小,3号基桩附加弯矩逐渐增大。(3)随土体损失率增大,底板竖向附加变形逐渐变大,3号基桩附加弯矩逐渐变大。(4)施工完毕后,除4号桩(两隧道之间)外,其余各桩水平变形规律为靠近隧道的两排桩累积变形最大,离隧道越远,桩体变形越小,4号桩体最终附加水平变形倾向于先期开挖的左线隧道。

Study on the Influence of Metro Tunnel Shield Construction on the Pile Box Building

In order to ensure the safety of metro double track shield tunneling under pile box foundation buildings,the finite element software ABAQUS is used to establish the calculation model and simulate the law of additional pile foundation and foundation soleplate deformation and the additional internal forces in terms of different pile length,pile diameter and rate of soil loss and under different working conditions so as to provide references for the design of tunneling under pile box foundation buildings. The results showed that:( 1) with the increase of the pile length,the vertical deformation of the foundation soleplate and the additional bending moment gradually become smaller,and the vertical additional bending moment of the foundation soleplate appears maximum value at the top of the pile; the 3 号 pile( right track tunnel on the left) increases with the increasing of pile length,the maximum horizontal displacement of the pile body,the additional bending moment and the additional axial force decrease gradually;( 2) with the increase of the pile diameter,the vertical additional deformation of the foundation soleplate gradually increases,the additional bending moment of 3 号 pile decreases gradually;( 3) with the increase of the soil loss rate,the vertical additional deformation of the foundation soleplate becomes larger,the additional bending moment of 3 号 pile increases gradually;( 4) after the completion of construction, the deformation of the remaining piles is the largest in the two row piles near the tunnel except 4 号 pile( between the two tunnels),the farther away from the tunnel,the smaller the pile deformation; the final additional horizontal deformation of 4 号 pile body tends to appear in the pre-excavated left track tunnel.